diff --git a/modules/ppcp-api-client/src/Factory/ReturnUrlFactory.php b/modules/ppcp-api-client/src/Factory/ReturnUrlFactory.php
index cba03352f7..d80f8094d8 100644
--- a/modules/ppcp-api-client/src/Factory/ReturnUrlFactory.php
+++ b/modules/ppcp-api-client/src/Factory/ReturnUrlFactory.php
@@ -1,9 +1,4 @@
 <?php
-/**
- * Factory for determining the appropriate return URL based on context.
- *
- * @package WooCommerce\PayPalCommerce\ApiClient\Factory
- */
 
 declare(strict_types=1);
 
@@ -12,14 +7,34 @@
 use WooCommerce\PayPalCommerce\ApiClient\Exception\RuntimeException;
 
 /**
- * Class ReturnUrlFactory
+ * Factory for determining the appropriate return URL based on context.
  */
 class ReturnUrlFactory {
+	public const PCP_QUERY_ARG = 'pcp-return';
 
 	/**
+	 * @param string                $context The context, like in ContextTrait.
+	 * @param array<string, mixed>  $request_data The request parameters, if exist.
+	 *  'order_id`, 'purchase_units' etc.
+	 * @param array<string, string> $custom_query_args Additional query args to add into the URL.
+	 *
 	 * @throws RuntimeException When required data is missing for the context.
 	 */
-	public function from_context( string $context, array $request_data = array() ): string {
+	public function from_context(
+		string $context,
+		array $request_data = array(),
+		array $custom_query_args = array()
+	): string {
+		return add_query_arg(
+			array_merge(
+				array( self::PCP_QUERY_ARG => 'button' ),
+				$custom_query_args
+			),
+			$this->wc_url_from_context( $context, $request_data )
+		);
+	}
+
+	protected function wc_url_from_context( string $context, array $request_data = array() ): string {
 		switch ( $context ) {
 			case 'cart':
 			case 'cart-block':
diff --git a/modules/ppcp-blocks/resources/js/Components/paypal.js b/modules/ppcp-blocks/resources/js/Components/paypal.js
index 92287381fc..f2185f0b72 100644
--- a/modules/ppcp-blocks/resources/js/Components/paypal.js
+++ b/modules/ppcp-blocks/resources/js/Components/paypal.js
@@ -21,6 +21,7 @@ import {
 	onApproveSavePayment,
 } from '../paypal-config';
 import { useRef } from 'react';
+import Spinner from '../../../../ppcp-button/resources/js/modules/Helper/Spinner';
 
 const PAYPAL_GATEWAY_ID = 'ppcp-gateway';
 
@@ -52,8 +53,11 @@ export const PayPalComponent = ( {
 		useState( false );
 
 	const [ paypalScriptLoaded, setPaypalScriptLoaded ] = useState( false );
+	const [ isFullPageSpinnerActive, setIsFullPageSpinnerActive ] =
+		useState( false );
 
 	const paypalButtonRef = useRef( null );
+	const spinnerRef = useRef( null );
 
 	if ( ! paypalScriptLoaded ) {
 		if ( ! paypalScriptPromise ) {
@@ -70,6 +74,18 @@ export const PayPalComponent = ( {
 		? `${ config.id }-${ fundingSource }`
 		: config.id;
 
+	// Full-page spinner used to block UI interactions during flows like AppSwitch.
+	useEffect( () => {
+		if ( isFullPageSpinnerActive ) {
+			if ( ! spinnerRef.current ) {
+				spinnerRef.current = Spinner.fullPage();
+			}
+			spinnerRef.current.block();
+		} else if ( spinnerRef.current ) {
+			spinnerRef.current.unblock();
+		}
+	}, [ isFullPageSpinnerActive ] );
+
 	useEffect( () => {
 		// fill the form if in continuation (for product or mini-cart buttons)
 		if ( continuationFilled || ! config.scriptData.continuation?.order ) {
@@ -286,6 +302,14 @@ export const PayPalComponent = ( {
 		};
 	}, [ onPaymentSetup, paypalOrder, activePaymentMethod ] );
 
+	useEffect( () => {
+		const unsubscribe = onCheckoutFail( () => {
+			setIsFullPageSpinnerActive( false );
+		} );
+
+		return unsubscribe;
+	}, [ onCheckoutFail ] );
+
 	useEffect( () => {
 		if ( activePaymentMethod !== methodId ) {
 			return;
@@ -336,7 +360,8 @@ export const PayPalComponent = ( {
 						setGotoContinuationOnError,
 						onSubmit,
 						onError,
-						onClose
+						onClose,
+						setIsFullPageSpinnerActive
 					);
 				},
 			}
@@ -491,7 +516,8 @@ export const PayPalComponent = ( {
 					setGotoContinuationOnError,
 					onSubmit,
 					onError,
-					onClose
+					onClose,
+					setIsFullPageSpinnerActive
 				)
 			}
 			onShippingOptionsChange={ getOnShippingOptionsChange(
diff --git a/modules/ppcp-blocks/resources/js/paypal-config.js b/modules/ppcp-blocks/resources/js/paypal-config.js
index 4aacab3180..93105786fe 100644
--- a/modules/ppcp-blocks/resources/js/paypal-config.js
+++ b/modules/ppcp-blocks/resources/js/paypal-config.js
@@ -64,8 +64,11 @@ export const handleApprove = async (
 	setGotoContinuationOnError,
 	onSubmit,
 	onError,
-	onClose
+	onClose,
+	setIsFullPageSpinnerActive
 ) => {
+	setIsFullPageSpinnerActive( true );
+
 	try {
 		let order;
 
@@ -168,6 +171,8 @@ export const handleApprove = async (
 	} catch ( err ) {
 		console.error( err );
 
+		setIsFullPageSpinnerActive( false );
+
 		onError( err.message );
 
 		onClose();
diff --git a/modules/ppcp-button/resources/js/modules/ContextBootstrap/SingleProductBootstrap.js b/modules/ppcp-button/resources/js/modules/ContextBootstrap/SingleProductBootstrap.js
index ef51b32d5a..87dadb4686 100644
--- a/modules/ppcp-button/resources/js/modules/ContextBootstrap/SingleProductBootstrap.js
+++ b/modules/ppcp-button/resources/js/modules/ContextBootstrap/SingleProductBootstrap.js
@@ -8,6 +8,7 @@ import SimulateCart from '../Helper/SimulateCart';
 import { strRemoveWord, strAddWord, throttle } from '../Helper/Utils';
 import merge from 'deepmerge';
 import { debounce } from '../../../../../ppcp-blocks/resources/js/Helper/debounce';
+import ResumeFlowHelper from '../Helper/ResumeFlowHelper';
 
 class SingleProductBootstrap {
 	constructor( gateway, renderer, errorHandler ) {
@@ -53,7 +54,10 @@ class SingleProductBootstrap {
 			return;
 		}
 
-		this.render();
+		// Avoid re-rendering during the resume flow to prevent duplicate onApprove callbacks.
+		if ( ! ResumeFlowHelper.isResumeFlow() ) {
+			this.render();
+		}
 
 		this.renderer.enableSmartButtons( this.gateway.button.wrapper );
 		show( this.gateway.button.wrapper );
diff --git a/modules/ppcp-button/resources/js/modules/Helper/Spinner.js b/modules/ppcp-button/resources/js/modules/Helper/Spinner.js
index 30d0830f90..63f9412792 100644
--- a/modules/ppcp-button/resources/js/modules/Helper/Spinner.js
+++ b/modules/ppcp-button/resources/js/modules/Helper/Spinner.js
@@ -14,12 +14,16 @@ class Spinner {
 				background: '#fff',
 				opacity: 0.6,
 			},
+			baseZ: 10000,
 		} );
 	}
 
 	unblock() {
 		jQuery( this.target ).unblock();
 	}
-}
 
+	static fullPage() {
+		return new Spinner( window );
+	}
+}
 export default Spinner;
diff --git a/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForContinue.js b/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForContinue.js
index 13b914335d..d5c5ab6dcb 100644
--- a/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForContinue.js
+++ b/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForContinue.js
@@ -1,3 +1,5 @@
+import Spinner from '../Helper/Spinner';
+
 const initiateRedirect = ( successUrl ) => {
 	/**
 	 * Notice how this step initiates a redirect to a new page using a plain
@@ -15,6 +17,10 @@ const initiateRedirect = ( successUrl ) => {
 
 const onApprove = ( context, errorHandler ) => {
 	return ( data, actions ) => {
+		// Block the entire page during approval process
+		const spinner = Spinner.fullPage();
+		spinner.block();
+
 		const canCreateOrder =
 			! context.config.vaultingEnabled || data.paymentSource !== 'venmo';
 
@@ -50,6 +56,9 @@ const onApprove = ( context, errorHandler ) => {
 
 				const orderReceivedUrl = approveData.data?.order_received_url;
 				initiateRedirect( orderReceivedUrl || context.config.redirect );
+			} )
+			.finally( () => {
+				spinner.unblock();
 			} );
 	};
 };
diff --git a/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForPayNow.js b/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForPayNow.js
index 629e8871aa..b64f89f201 100644
--- a/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForPayNow.js
+++ b/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForPayNow.js
@@ -1,3 +1,8 @@
+import {
+	getCurrentPaymentMethod,
+	PaymentMethods,
+} from '../Helper/CheckoutMethodState';
+
 const onApprove = ( context, errorHandler, spinner ) => {
 	return ( data, actions ) => {
 		spinner.block();
@@ -34,6 +39,15 @@ const onApprove = ( context, errorHandler, spinner ) => {
 					}
 					throw new Error( data.data.message );
 				}
+
+				// in some cases a different method may get selected,
+				// such as when returning from AppSwitch in a different browser and PayPal is not default
+				if ( ! getCurrentPaymentMethod().startsWith( 'ppcp-' ) ) {
+					jQuery(
+						`input[name="payment_method"][value="${ PaymentMethods.PAYPAL }"]`
+					).prop( 'checked', true );
+				}
+
 				document.querySelector( '#place_order' ).click();
 			} );
 	};
diff --git a/modules/ppcp-button/services.php b/modules/ppcp-button/services.php
index 0f02028ef0..da9a073912 100644
--- a/modules/ppcp-button/services.php
+++ b/modules/ppcp-button/services.php
@@ -18,6 +18,8 @@
 use WooCommerce\PayPalCommerce\Button\Helper\ContextTrait;
 use WooCommerce\PayPalCommerce\Button\Helper\DisabledFundingSources;
 use WooCommerce\PayPalCommerce\Button\Helper\WooCommerceOrderCreator;
+use WooCommerce\PayPalCommerce\Button\Session\CartDataFactory;
+use WooCommerce\PayPalCommerce\Button\Session\CartDataTransientStorage;
 use WooCommerce\PayPalCommerce\Button\Validation\CheckoutFormValidator;
 use WooCommerce\PayPalCommerce\Button\Endpoint\ValidateCheckoutEndpoint;
 use WooCommerce\PayPalCommerce\Session\SessionHandler;
@@ -236,6 +238,8 @@ public function get_context(): string {
 			$session_handler,
 			$settings,
 			$early_order_handler,
+			$container->get( 'button.session.factory.card-data' ),
+			$container->get( 'button.session.storage.card-data.transient' ),
 			$registration_needed,
 			$container->get( 'wcgateway.settings.card_billing_data_mode' ),
 			$container->get( 'button.early-wc-checkout-validation-enabled' ),
@@ -407,7 +411,15 @@ public function get_context(): string {
 		return new WooCommerceOrderCreator(
 			$container->get( 'wcgateway.funding-source.renderer' ),
 			$container->get( 'session.handler' ),
-			$container->get( 'wc-subscriptions.helper' )
+			$container->get( 'wc-subscriptions.helper' ),
+			$container->get( 'button.session.factory.card-data' )
 		);
 	},
+
+	'button.session.factory.card-data'            => static function ( ContainerInterface $container ): CartDataFactory {
+		return new CartDataFactory();
+	},
+	'button.session.storage.card-data.transient'  => static function ( ContainerInterface $container ): CartDataTransientStorage {
+		return new CartDataTransientStorage();
+	},
 );
diff --git a/modules/ppcp-button/src/ButtonModule.php b/modules/ppcp-button/src/ButtonModule.php
index cb3110329c..fbbe3e3884 100644
--- a/modules/ppcp-button/src/ButtonModule.php
+++ b/modules/ppcp-button/src/ButtonModule.php
@@ -9,6 +9,8 @@
 
 namespace WooCommerce\PayPalCommerce\Button;
 
+use WooCommerce\PayPalCommerce\ApiClient\Endpoint\OrderEndpoint;
+use WooCommerce\PayPalCommerce\ApiClient\Factory\ReturnUrlFactory;
 use WooCommerce\PayPalCommerce\Button\Endpoint\ApproveSubscriptionEndpoint;
 use WooCommerce\PayPalCommerce\Button\Endpoint\CartScriptParamsEndpoint;
 use WooCommerce\PayPalCommerce\Button\Endpoint\SaveCheckoutFormEndpoint;
@@ -22,6 +24,8 @@
 use WooCommerce\PayPalCommerce\Button\Endpoint\GetOrderEndpoint;
 use WooCommerce\PayPalCommerce\Button\Endpoint\StartPayPalVaultingEndpoint;
 use WooCommerce\PayPalCommerce\Button\Helper\EarlyOrderHandler;
+use WooCommerce\PayPalCommerce\Button\Helper\WooCommerceOrderCreator;
+use WooCommerce\PayPalCommerce\Button\Session\CartDataTransientStorage;
 use WooCommerce\PayPalCommerce\Vendor\Inpsyde\Modularity\Module\ExecutableModule;
 use WooCommerce\PayPalCommerce\Vendor\Inpsyde\Modularity\Module\ExtendingModule;
 use WooCommerce\PayPalCommerce\Vendor\Inpsyde\Modularity\Module\ModuleClassNameIdTrait;
@@ -98,6 +102,8 @@ static function ( $value ) use ( $c ) {
 
 		$this->register_ajax_endpoints( $c );
 
+		$this->register_appswitch_crossbrowser_handler( $c );
+
 		return true;
 	}
 
@@ -228,4 +234,75 @@ static function () use ( $container ) {
 			}
 		);
 	}
+
+	private function register_appswitch_crossbrowser_handler( ContainerInterface $container ): void {
+		if ( ! $container->get( 'wcgateway.appswitch-enabled' ) ) {
+			return;
+		}
+
+		// After returning from cross-browser AppSwitch (started in non-default browser, then redirected to the default one)
+		// we need to retrieve the saved cart and PayPal order, create a WC order and redirect to Pay for order.
+		add_action(
+			'wp',
+			static function () use ( $container ) {
+				// phpcs:ignore WordPress.Security.NonceVerification
+				if ( ! isset( $_GET[ ReturnUrlFactory::PCP_QUERY_ARG ] ) ) {
+					return;
+				}
+
+				if ( is_checkout_pay_page() ) {
+					return;
+				}
+
+				// phpcs:ignore WordPress.Security.NonceVerification
+				if ( ! isset( $_GET[ CreateOrderEndpoint::RETURN_URL_CART_QUERY_ARG ] ) ) {
+					return;
+				}
+
+				// phpcs:ignore WordPress.Security.NonceVerification
+				$cart_key = wc_clean( wp_unslash( $_GET[ CreateOrderEndpoint::RETURN_URL_CART_QUERY_ARG ] ) );
+				if ( ! is_string( $cart_key ) ) {
+					return;
+				}
+
+				$card_data_storage = $container->get( 'button.session.storage.card-data.transient' );
+				assert( $card_data_storage instanceof CartDataTransientStorage );
+
+				$cart_data = $card_data_storage->get( $cart_key );
+				if ( ! $cart_data ) {
+					return;
+				}
+
+				// Delete the data to avoid accidentally triggering it again, duplicating orders etc.
+				$card_data_storage->remove( $cart_data );
+
+				if ( ! WC()->cart ) {
+					return;
+				}
+				// The current cart is the same, so we don't need to do anything (probably not cross-browser).
+				if ( WC()->cart->get_cart_hash() === $cart_data->cart_hash() ) {
+					return;
+				}
+
+				$paypal_order_id = $cart_data->paypal_order_id();
+				if ( empty( $paypal_order_id ) ) {
+					return;
+				}
+
+				$order_endpoint = $container->get( 'api.endpoint.order' );
+				assert( $order_endpoint instanceof OrderEndpoint );
+
+				$paypal_order = $order_endpoint->order( $paypal_order_id );
+
+				$wc_order_creator = $container->get( 'button.helper.wc-order-creator' );
+				assert( $wc_order_creator instanceof WooCommerceOrderCreator );
+
+				$wc_order = $wc_order_creator->create_from_paypal_order( $paypal_order, $cart_data );
+
+				// Redirect via JS because we need to keep the # parameters which are not accessible on the server side.
+				// phpcs:ignore WordPress.Security.EscapeOutput
+				echo "<script>location.href = '" . $wc_order->get_checkout_payment_url() . "' + location.hash;</script>";
+			}
+		);
+	}
 }
diff --git a/modules/ppcp-button/src/Endpoint/CreateOrderEndpoint.php b/modules/ppcp-button/src/Endpoint/CreateOrderEndpoint.php
index 818c22a4b8..a409350734 100644
--- a/modules/ppcp-button/src/Endpoint/CreateOrderEndpoint.php
+++ b/modules/ppcp-button/src/Endpoint/CreateOrderEndpoint.php
@@ -30,6 +30,8 @@
 use WooCommerce\PayPalCommerce\ApiClient\Factory\ReturnUrlFactory;
 use WooCommerce\PayPalCommerce\ApiClient\Factory\ShippingPreferenceFactory;
 use WooCommerce\PayPalCommerce\Button\Exception\ValidationException;
+use WooCommerce\PayPalCommerce\Button\Session\CartDataFactory;
+use WooCommerce\PayPalCommerce\Button\Session\CartDataTransientStorage;
 use WooCommerce\PayPalCommerce\Button\Validation\CheckoutFormValidator;
 use WooCommerce\PayPalCommerce\Button\Helper\EarlyOrderHandler;
 use WooCommerce\PayPalCommerce\Session\SessionHandler;
@@ -50,6 +52,8 @@ class CreateOrderEndpoint implements EndpointInterface {
 
 	const ENDPOINT = 'ppc-create-order';
 
+	public const RETURN_URL_CART_QUERY_ARG = 'pcp-cart';
+
 	/**
 	 * The request data helper.
 	 *
@@ -118,6 +122,10 @@ class CreateOrderEndpoint implements EndpointInterface {
 	 */
 	private $early_order_handler;
 
+	protected CartDataFactory $cart_data_factory;
+
+	protected CartDataTransientStorage $cart_data_transient_storage;
+
 	/**
 	 * Data from the request.
 	 *
@@ -207,6 +215,8 @@ class CreateOrderEndpoint implements EndpointInterface {
 	 * @param SessionHandler            $session_handler The SessionHandler object.
 	 * @param Settings                  $settings The Settings object.
 	 * @param EarlyOrderHandler         $early_order_handler The EarlyOrderHandler object.
+	 * @param CartDataFactory           $cart_data_factory
+	 * @param CartDataTransientStorage  $cart_data_transient_storage
 	 * @param bool                      $registration_needed  Whether a new user must be registered during checkout.
 	 * @param string                    $card_billing_data_mode The value of card_billing_data_mode from the settings.
 	 * @param bool                      $early_validation_enabled Whether to execute WC validation of the checkout form.
@@ -228,6 +238,8 @@ public function __construct(
 		SessionHandler $session_handler,
 		Settings $settings,
 		EarlyOrderHandler $early_order_handler,
+		CartDataFactory $cart_data_factory,
+		CartDataTransientStorage $cart_data_transient_storage,
 		bool $registration_needed,
 		string $card_billing_data_mode,
 		bool $early_validation_enabled,
@@ -249,6 +261,8 @@ public function __construct(
 		$this->session_handler                       = $session_handler;
 		$this->settings                              = $settings;
 		$this->early_order_handler                   = $early_order_handler;
+		$this->cart_data_factory                     = $cart_data_factory;
+		$this->cart_data_transient_storage           = $cart_data_transient_storage;
 		$this->registration_needed                   = $registration_needed;
 		$this->card_billing_data_mode                = $card_billing_data_mode;
 		$this->early_validation_enabled              = $early_validation_enabled;
@@ -475,33 +489,52 @@ private function create_paypal_order( ?WC_Order $wc_order = null, string $paymen
 			$payment_source_key
 		);
 
+		$custom_args = array();
+
+		$cart_data = null;
+		// Save the cart to be able to access it after cross-browser AppSwitch.
+		if ( 'pay-now' !== $data['context'] ) {
+			try {
+				$cart_data = $this->cart_data_factory->from_current_cart();
+				$cart_data->generate_key();
+
+				$key = $cart_data->key();
+				assert( ! empty( $key ) );
+
+				$custom_args[ self::RETURN_URL_CART_QUERY_ARG ] = $key;
+			} catch ( Throwable $exception ) {
+				$this->logger->error( 'Failed to serialize cart: ' . $exception->getMessage() );
+			}
+		}
+
+		$return_url = $this->return_url_factory->from_context(
+			$this->parsed_request_data['context'],
+			$this->parsed_request_data,
+			$custom_args
+		);
+
 		$experience_context = $this->experience_context_builder
 			->with_default_paypal_config( $shipping_preference, $action )
-			->with_contact_preference( $contact_preference );
+			->with_contact_preference( $contact_preference )
+			->with_custom_return_url( $return_url )
+			->with_custom_cancel_url( $return_url );
 
 		if ( $this->server_side_shipping_callback_enabled
 			&& $shipping_preference === ExperienceContext::SHIPPING_PREFERENCE_GET_FROM_FILE ) {
 			$experience_context = $experience_context->with_shipping_callback();
 		}
 
-		$return_url = $this->return_url_factory->from_context(
-			$this->parsed_request_data['context'],
-			$this->parsed_request_data
-		);
-
 		$payment_source = new PaymentSource(
 			$payment_source_key,
 			(object) array(
 				'experience_context' => $experience_context
-					->with_custom_return_url( $return_url )
-					->with_custom_cancel_url( $return_url )
 					->build()
 					->to_array(),
 			)
 		);
 
 		try {
-			return $this->api_endpoint->create(
+			$order = $this->api_endpoint->create(
 				array( $this->purchase_unit ),
 				$shipping_preference,
 				$payer,
@@ -524,7 +557,7 @@ function ( stdClass $detail ): bool {
 
 				$this->purchase_unit->set_shipping( null );
 
-				return $this->api_endpoint->create(
+				$order = $this->api_endpoint->create(
 					array( $this->purchase_unit ),
 					$shipping_preference,
 					$payer,
@@ -532,10 +565,21 @@ function ( stdClass $detail ): bool {
 					$data,
 					$payment_source
 				);
+			} else {
+				throw $exception;
 			}
+		}
 
-			throw $exception;
+		if ( $cart_data ) {
+			try {
+				$cart_data->set_paypal_order_id( $order->id() );
+				$this->cart_data_transient_storage->save( $cart_data );
+			} catch ( Throwable $exception ) {
+				$this->logger->error( 'Failed to save cart: ' . $exception->getMessage() );
+			}
 		}
+
+		return $order;
 	}
 
 	/**
diff --git a/modules/ppcp-button/src/Helper/WooCommerceOrderCreator.php b/modules/ppcp-button/src/Helper/WooCommerceOrderCreator.php
index 052afe46d3..10b7905673 100644
--- a/modules/ppcp-button/src/Helper/WooCommerceOrderCreator.php
+++ b/modules/ppcp-button/src/Helper/WooCommerceOrderCreator.php
@@ -24,6 +24,8 @@
 use WooCommerce\PayPalCommerce\ApiClient\Entity\Order;
 use WooCommerce\PayPalCommerce\ApiClient\Entity\Payer;
 use WooCommerce\PayPalCommerce\ApiClient\Entity\Shipping;
+use WooCommerce\PayPalCommerce\Button\Session\CartData;
+use WooCommerce\PayPalCommerce\Button\Session\CartDataFactory;
 use WooCommerce\PayPalCommerce\Session\SessionHandler;
 use WooCommerce\PayPalCommerce\WcGateway\FundingSource\FundingSourceRenderer;
 use WooCommerce\PayPalCommerce\WcGateway\Gateway\PayPalGateway;
@@ -56,32 +58,33 @@ class WooCommerceOrderCreator {
 	 */
 	protected $subscription_helper;
 
-	/**
-	 * WooCommerceOrderCreator constructor.
-	 *
-	 * @param FundingSourceRenderer $funding_source_renderer The funding source renderer.
-	 * @param SessionHandler        $session_handler The session handler.
-	 * @param SubscriptionHelper    $subscription_helper The subscription helper.
-	 */
+	protected CartDataFactory $cart_data_factory;
+
 	public function __construct(
 		FundingSourceRenderer $funding_source_renderer,
 		SessionHandler $session_handler,
-		SubscriptionHelper $subscription_helper
+		SubscriptionHelper $subscription_helper,
+		CartDataFactory $cart_data_factory
 	) {
 		$this->funding_source_renderer = $funding_source_renderer;
 		$this->session_handler         = $session_handler;
 		$this->subscription_helper     = $subscription_helper;
+		$this->cart_data_factory       = $cart_data_factory;
 	}
 
 	/**
 	 * Creates WC order based on given PayPal order.
 	 *
-	 * @param Order   $order The PayPal order.
-	 * @param WC_Cart $wc_cart The Cart.
-	 * @return WC_Order The WC order.
+	 * @param Order            $order The PayPal order.
+	 * @param WC_Cart|CartData $cart The WC cart (converted into CartData).
 	 * @throws RuntimeException If problem creating.
 	 */
-	public function create_from_paypal_order( Order $order, WC_Cart $wc_cart ): WC_Order {
+	public function create_from_paypal_order( Order $order, $cart ): WC_Order {
+		$cart_data = $cart;
+		if ( $cart_data instanceof WC_Cart ) {
+			$cart_data = $this->cart_data_factory->from_current_cart( $cart_data );
+		}
+
 		$wc_order = wc_create_order();
 
 		if ( ! $wc_order instanceof WC_Order ) {
@@ -95,9 +98,9 @@ public function create_from_paypal_order( Order $order, WC_Cart $wc_cart ): WC_O
 
 			$this->configure_payment_source( $wc_order );
 			$this->configure_customer( $wc_order );
-			$this->configure_line_items( $wc_order, $wc_cart, $payer, $shipping );
-			$this->configure_addresses( $wc_order, $payer, $shipping, $wc_cart );
-			$this->configure_coupons( $wc_order, $wc_cart->get_applied_coupons() );
+			$this->configure_line_items( $wc_order, $cart_data, $payer, $shipping );
+			$this->configure_addresses( $wc_order, $payer, $shipping, $cart_data->needs_shipping() );
+			$this->configure_coupons( $wc_order, $cart_data->coupons() );
 
 			$wc_order->calculate_totals();
 			$wc_order->save();
@@ -106,7 +109,7 @@ public function create_from_paypal_order( Order $order, WC_Cart $wc_cart ): WC_O
 			throw new RuntimeException( 'Failed to create WooCommerce order: ' . $exception->getMessage() );
 		}
 
-		do_action( 'woocommerce_paypal_payments_shipping_callback_woocommerce_order_created', $wc_order, $wc_cart );
+		do_action( 'woocommerce_paypal_payments_woocommerce_order_created_from_cart', $wc_order, $cart_data );
 
 		return $wc_order;
 	}
@@ -114,17 +117,10 @@ public function create_from_paypal_order( Order $order, WC_Cart $wc_cart ): WC_O
 	/**
 	 * Configures the line items.
 	 *
-	 * @param WC_Order      $wc_order The WC order.
-	 * @param WC_Cart       $wc_cart The Cart.
-	 * @param Payer|null    $payer The payer.
-	 * @param Shipping|null $shipping The shipping.
-	 * @return void
 	 * @psalm-suppress InvalidScalarArgument
 	 */
-	protected function configure_line_items( WC_Order $wc_order, WC_Cart $wc_cart, ?Payer $payer, ?Shipping $shipping ): void {
-		$cart_contents = $wc_cart->get_cart();
-
-		foreach ( $cart_contents as $cart_item ) {
+	protected function configure_line_items( WC_Order $wc_order, CartData $cart_data, ?Payer $payer, ?Shipping $shipping ): void {
+		foreach ( $cart_data->items() as $cart_item ) {
 			$product_id           = $cart_item['product_id'] ?? 0;
 			$variation_id         = $cart_item['variation_id'] ?? 0;
 			$quantity             = $cart_item['quantity'] ?? 0;
@@ -173,9 +169,9 @@ protected function configure_line_items( WC_Order $wc_order, WC_Cart $wc_cart, ?
 				$item->set_total( $subscription_total );
 
 				$subscription->add_product( $product );
-				$this->configure_addresses( $subscription, $payer, $shipping, $wc_cart );
+				$this->configure_addresses( $subscription, $payer, $shipping, $cart_data->needs_shipping() );
 				$this->configure_payment_source( $subscription );
-				$this->configure_coupons( $subscription, $wc_cart->get_applied_coupons() );
+				$this->configure_coupons( $subscription, $cart_data->coupons() );
 
 				$dates = array(
 					'trial_end'    => WC_Subscriptions_Product::get_trial_expiration_date( $product_id ),
@@ -195,15 +191,10 @@ protected function configure_line_items( WC_Order $wc_order, WC_Cart $wc_cart, ?
 	/**
 	 * Configures the shipping & billing addresses for WC order from given payer.
 	 *
-	 * @param WC_Order      $wc_order The WC order.
-	 * @param Payer|null    $payer The payer.
-	 * @param Shipping|null $shipping The shipping.
-	 * @param WC_Cart       $wc_cart The Cart.
-	 * @return void
 	 * @throws WC_Data_Exception|RuntimeException When failing to configure shipping.
 	 * @psalm-suppress RedundantConditionGivenDocblockType
 	 */
-	protected function configure_addresses( WC_Order $wc_order, ?Payer $payer, ?Shipping $shipping, WC_Cart $wc_cart ): void {
+	protected function configure_addresses( WC_Order $wc_order, ?Payer $payer, ?Shipping $shipping, bool $needs_shipping ): void {
 		$shipping_address = null;
 		$billing_address  = null;
 		$shipping_options = null;
@@ -253,7 +244,7 @@ protected function configure_addresses( WC_Order $wc_order, ?Payer $payer, ?Ship
 			$shipping_options = $shipping->options()[0] ?? '';
 		}
 
-		if ( $wc_cart->needs_shipping() && empty( $shipping_options ) ) {
+		if ( $needs_shipping && empty( $shipping_options ) ) {
 			throw new RuntimeException( 'No shipping method has been selected.' );
 		}
 
diff --git a/modules/ppcp-button/src/Session/CartData.php b/modules/ppcp-button/src/Session/CartData.php
new file mode 100644
index 0000000000..8f5ad1b66e
--- /dev/null
+++ b/modules/ppcp-button/src/Session/CartData.php
@@ -0,0 +1,114 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WooCommerce\PayPalCommerce\Button\Session;
+
+/**
+ * Contains a snapshot of the WC cart data, e.g. for saving it and creating an order later.
+ */
+class CartData {
+	protected ?string $key = null;
+
+	/**
+	 * @var array<string, array<string, mixed>>
+	 */
+	protected array $items;
+
+	/**
+	 * @var string[]
+	 */
+	protected array $coupons;
+
+	protected bool $needs_shipping;
+
+	protected string $cart_hash;
+
+	protected ?string $paypal_order_id = null;
+
+	/**
+	 * @param array<string, array<string, mixed>> $items The cart items like in $cart->get_cart_for_session() or $cart->get_cart().
+	 * @param string[]                            $coupons
+	 * @param bool                                $needs_shipping
+	 * @param string                              $cart_hash
+	 */
+	public function __construct(
+		array $items,
+		array $coupons,
+		bool $needs_shipping,
+		string $cart_hash
+	) {
+		$this->items          = $items;
+		$this->coupons        = $coupons;
+		$this->needs_shipping = $needs_shipping;
+		$this->cart_hash      = $cart_hash;
+	}
+
+	/**
+	 * Generates a new random key.
+	 */
+	public function generate_key(): void {
+		$this->key = uniqid( '', true );
+	}
+
+	/**
+	 * Returns the key that can be used for identifying the instance in storage.
+	 */
+	public function key(): ?string {
+		return $this->key;
+	}
+
+	/**
+	 * The cart items like in $cart->get_cart_for_session() or $cart->get_cart().
+	 *
+	 * @return array<string, array<string, mixed>>
+	 */
+	public function items(): array {
+		return $this->items;
+	}
+
+	/**
+	 * @return string[]
+	 */
+	public function coupons(): array {
+		return $this->coupons;
+	}
+
+	public function needs_shipping(): bool {
+		return $this->needs_shipping;
+	}
+
+	public function cart_hash(): string {
+		return $this->cart_hash;
+	}
+
+	public function set_paypal_order_id( ?string $paypal_order_id ): void {
+		$this->paypal_order_id = $paypal_order_id;
+	}
+
+	public function paypal_order_id(): ?string {
+		return $this->paypal_order_id;
+	}
+
+	public function to_array(): array {
+		return array(
+			'items'           => $this->items,
+			'coupons'         => $this->coupons,
+			'needs_shipping'  => $this->needs_shipping,
+			'cart_hash'       => $this->cart_hash,
+			'paypal_order_id' => $this->paypal_order_id,
+		);
+	}
+
+	public static function from_array( array $data, ?string $key = null ): CartData {
+		$cart_data                  = new CartData(
+			$data['items'] ?? array(),
+			$data['coupons'] ?? array(),
+			(bool) ( $data['needs_shipping'] ?? false ),
+			$data['cart_hash'] ?? ''
+		);
+		$cart_data->paypal_order_id = $data['paypal_order_id'] ?? null;
+		$cart_data->key             = $key;
+		return $cart_data;
+	}
+}
diff --git a/modules/ppcp-button/src/Session/CartDataFactory.php b/modules/ppcp-button/src/Session/CartDataFactory.php
new file mode 100644
index 0000000000..de5ef6b6fe
--- /dev/null
+++ b/modules/ppcp-button/src/Session/CartDataFactory.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WooCommerce\PayPalCommerce\Button\Session;
+
+use Exception;
+use WC_Cart;
+
+/**
+ * Creates CartData.
+ */
+class CartDataFactory {
+	/**
+	 * Creates CartData from the WC cart.
+	 *
+	 * @throws Exception If WC cart is missing.
+	 */
+	public function from_current_cart( ?WC_Cart $cart = null ): CartData {
+		if ( ! $cart ) {
+			$cart = WC()->cart;
+			if ( ! $cart instanceof WC_Cart ) {
+				throw new Exception( 'Cart not found.' );
+			}
+		}
+
+		return new CartData(
+			$cart->get_cart_for_session(),
+			$cart->get_applied_coupons(),
+			$cart->needs_shipping(),
+			$cart->get_cart_hash()
+		);
+	}
+}
diff --git a/modules/ppcp-button/src/Session/CartDataTransientStorage.php b/modules/ppcp-button/src/Session/CartDataTransientStorage.php
new file mode 100644
index 0000000000..ca1c202c44
--- /dev/null
+++ b/modules/ppcp-button/src/Session/CartDataTransientStorage.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WooCommerce\PayPalCommerce\Button\Session;
+
+use Exception;
+
+/**
+ * Handles saving of CartData into WP transients.
+ */
+class CartDataTransientStorage {
+	protected int $expiration = 2 * HOUR_IN_SECONDS;
+
+	/**
+	 * @throws Exception If saving failed.
+	 */
+	public function save( CartData $cart_data ): void {
+		if ( empty( $cart_data->key() ) ) {
+			$cart_data->generate_key();
+		}
+
+		$key = $cart_data->key();
+		assert( ! empty( $key ) );
+
+		if ( ! set_transient( $key, $cart_data->to_array(), $this->expiration ) ) {
+			throw new Exception( 'set_transient failed.' );
+		}
+	}
+
+	public function get( string $key ): ?CartData {
+		$data = get_transient( $key );
+		if ( ! is_array( $data ) ) {
+			return null;
+		}
+
+		return CartData::from_array( $data, $key );
+	}
+
+	public function remove( CartData $cart_data ): void {
+		$key = $cart_data->key();
+		if ( empty( $key ) ) {
+			return;
+		}
+		delete_transient( $key );
+	}
+}
diff --git a/modules/ppcp-compat/src/CompatModule.php b/modules/ppcp-compat/src/CompatModule.php
index 56f784f04f..83cf7075d7 100644
--- a/modules/ppcp-compat/src/CompatModule.php
+++ b/modules/ppcp-compat/src/CompatModule.php
@@ -13,9 +13,10 @@
 use WC_Cart;
 use WC_Order;
 use WC_Order_Item_Product;
+use WooCommerce\PayPalCommerce\Button\Session\CartData;
 use WooCommerce\PayPalCommerce\Button\Helper\MessagesApply;
-use WooCommerce\PayPalCommerce\Settings\Data\SettingsModel;
 use WooCommerce\PayPalCommerce\Settings\SettingsModule;
+use WooCommerce\PayPalCommerce\Settings\Data\SettingsModel;
 use WooCommerce\PayPalCommerce\Vendor\Inpsyde\Modularity\Module\ExecutableModule;
 use WooCommerce\PayPalCommerce\Vendor\Inpsyde\Modularity\Module\ExtendingModule;
 use WooCommerce\PayPalCommerce\Vendor\Inpsyde\Modularity\Module\ModuleClassNameIdTrait;
@@ -537,11 +538,10 @@ static function( string $total, array $cart_item ) {
 	 */
 	protected function initialize_wc_bookings_compat_layer( ContainerInterface $container ): void {
 		add_action(
-			'woocommerce_paypal_payments_shipping_callback_woocommerce_order_created',
-			static function ( WC_Order $wc_order, WC_Cart $wc_cart ) use ( $container ): void {
+			'woocommerce_paypal_payments_woocommerce_order_created_from_cart',
+			static function ( WC_Order $wc_order, CartData $cart_data ) use ( $container ): void {
 				try {
-					$cart_contents = $wc_cart->get_cart();
-					foreach ( $cart_contents as $cart_item ) {
+					foreach ( $cart_data->items() as $cart_item ) {
 						if ( empty( $cart_item['booking'] ) ) {
 							continue;
 						}
diff --git a/tests/PHPUnit/ApiClient/Factory/ReturnUrlFactoryTest.php b/tests/PHPUnit/ApiClient/Factory/ReturnUrlFactoryTest.php
index 734856357c..39ff7baaf9 100644
--- a/tests/PHPUnit/ApiClient/Factory/ReturnUrlFactoryTest.php
+++ b/tests/PHPUnit/ApiClient/Factory/ReturnUrlFactoryTest.php
@@ -16,6 +16,16 @@ public function setUp(): void
     {
         parent::setUp();
         $this->testee = new ReturnUrlFactory();
+
+		when('add_query_arg')->alias(function (array $args, string $url): string {
+			$query_parts = [];
+			foreach ($args as $key => $value) {
+				$query_parts[] = $key . '=' . $value;
+			}
+			return $url .
+				(strpos($url, '?') === false ? '?' : '&') .
+				implode('&', $query_parts);
+		});
     }
 
 	/**
@@ -27,7 +37,7 @@ public function testFromContextReturnsCartUrl(string $context)
 
 		$result = $this->testee->from_context($context);
 
-		$this->assertEquals('https://example.com/cart', $result);
+		$this->assertEquals('https://example.com/cart?pcp-return=button', $result);
 	}
 
     public function testFromContextProductReturnsProductUrl()
@@ -46,7 +56,7 @@ public function testFromContextProductReturnsProductUrl()
 
         $result = $this->testee->from_context('product', $request_data);
 
-        $this->assertEquals('https://example.com/product/123', $result);
+        $this->assertEquals('https://example.com/product/123?pcp-return=button', $result);
     }
 
     public function testFromContextProductThrowsExceptionWhenNoUrl()
@@ -80,7 +90,7 @@ public function testFromContextPayNowReturnsOrderPaymentUrl()
 
         $result = $this->testee->from_context('pay-now', $request_data);
 
-        $this->assertEquals('https://example.com/checkout/pay/123?key=abc', $result);
+        $this->assertEquals('https://example.com/checkout/pay/123?key=abc&pcp-return=button', $result);
     }
 
     public function testFromContextPayNowThrowsExceptionWhenOrderNotFound()
@@ -100,7 +110,7 @@ public function testFromContextCheckoutReturnsCheckoutUrl()
 
         $result = $this->testee->from_context('checkout');
 
-        $this->assertEquals('https://example.com/checkout', $result);
+        $this->assertEquals('https://example.com/checkout?pcp-return=button', $result);
     }
 
     public function testFromContextDefaultReturnsCheckoutUrl()
@@ -109,9 +119,18 @@ public function testFromContextDefaultReturnsCheckoutUrl()
 
         $result = $this->testee->from_context('unknown-context');
 
-        $this->assertEquals('https://example.com/checkout', $result);
+        $this->assertEquals('https://example.com/checkout?pcp-return=button', $result);
     }
 
+	public function testFromContextReturnsCartUrlWithCustomArgs()
+	{
+		when('wc_get_cart_url')->justReturn('https://example.com/cart');
+
+		$result = $this->testee->from_context('cart', [], ['session' => '123']);
+
+		$this->assertEquals('https://example.com/cart?pcp-return=button&session=123', $result);
+	}
+
 	public function cartContextProvider(): array
 	{
 		return [
diff --git a/tests/PHPUnit/Button/Endpoint/CreateOrderEndpointTest.php b/tests/PHPUnit/Button/Endpoint/CreateOrderEndpointTest.php
index ce07a84cd4..f31da0b9ba 100644
--- a/tests/PHPUnit/Button/Endpoint/CreateOrderEndpointTest.php
+++ b/tests/PHPUnit/Button/Endpoint/CreateOrderEndpointTest.php
@@ -15,6 +15,8 @@
 use WooCommerce\PayPalCommerce\ApiClient\Factory\ReturnUrlFactory;
 use WooCommerce\PayPalCommerce\ApiClient\Factory\ContactPreferenceFactory;
 use WooCommerce\PayPalCommerce\Button\Helper\EarlyOrderHandler;
+use WooCommerce\PayPalCommerce\Button\Session\CartDataFactory;
+use WooCommerce\PayPalCommerce\Button\Session\CartDataTransientStorage;
 use WooCommerce\PayPalCommerce\Session\SessionHandler;
 use WooCommerce\PayPalCommerce\TestCase;
 use WooCommerce\PayPalCommerce\WcGateway\CardBillingMode;
@@ -173,6 +175,8 @@ protected function mockTestee()
             $session_handler,
             $settings,
             $early_order_handler,
+			Mockery::mock(CartDataFactory::class),
+			Mockery::mock(CartDataTransientStorage::class),
 			false,
 			CardBillingMode::MINIMAL_INPUT,
 			false,
diff --git a/tests/PHPUnit/TestCase.php b/tests/PHPUnit/TestCase.php
index 9e743085ae..1cccfbc089 100644
--- a/tests/PHPUnit/TestCase.php
+++ b/tests/PHPUnit/TestCase.php
@@ -41,6 +41,11 @@ public function setUp(): void
 		when('delete_transient')->returnArg();
 		when('wcs_get_subscription')->returnArg();
 
+
+		if (!defined('HOUR_IN_SECONDS')) {
+			define('HOUR_IN_SECONDS', 60 * 60);
+		}
+
 		setUp();
 	}