diff --git a/.ci/scripts/build-qnn-sdk.sh b/.ci/scripts/build-qnn-sdk.sh
index 4518468f29c..c480cda6c5d 100755
--- a/.ci/scripts/build-qnn-sdk.sh
+++ b/.ci/scripts/build-qnn-sdk.sh
@@ -33,7 +33,6 @@ set_up_aot() {
       -DEXECUTORCH_BUILD_DEVTOOLS=ON \
       -DEXECUTORCH_BUILD_EXTENSION_MODULE=ON \
       -DEXECUTORCH_BUILD_EXTENSION_DATA_LOADER=ON \
-      -DEXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR=ON \
       -DEXECUTORCH_BUILD_EXTENSION_TENSOR=ON \
       -DEXECUTORCH_ENABLE_EVENT_TRACER=ON \
       -DPYTHON_EXECUTABLE=python3
diff --git a/.ci/scripts/test_llama_torchao_lowbit.sh b/.ci/scripts/test_llama_torchao_lowbit.sh
index 83bfc22ba09..266e0d84e56 100644
--- a/.ci/scripts/test_llama_torchao_lowbit.sh
+++ b/.ci/scripts/test_llama_torchao_lowbit.sh
@@ -30,7 +30,6 @@ cmake -DPYTHON_EXECUTABLE=python \
     -DCMAKE_BUILD_TYPE=Release \
     -DEXECUTORCH_BUILD_EXTENSION_DATA_LOADER=ON \
     -DEXECUTORCH_BUILD_EXTENSION_MODULE=ON \
-    -DEXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR=ON \
     -DEXECUTORCH_BUILD_EXTENSION_TENSOR=ON \
     -DEXECUTORCH_BUILD_XNNPACK=OFF \
     -DEXECUTORCH_BUILD_KERNELS_QUANTIZED=ON \
diff --git a/.ci/scripts/test_llava.sh b/.ci/scripts/test_llava.sh
index 43f7a7348b7..fb7ba802a9f 100644
--- a/.ci/scripts/test_llava.sh
+++ b/.ci/scripts/test_llava.sh
@@ -37,7 +37,6 @@ EXECUTORCH_COMMON_CMAKE_ARGS="                      \
         -DEXECUTORCH_ENABLE_LOGGING=ON              \
         -DEXECUTORCH_BUILD_EXTENSION_MODULE=ON      \
         -DEXECUTORCH_BUILD_EXTENSION_DATA_LOADER=ON \
-        -DEXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR=ON \
         -DEXECUTORCH_BUILD_EXTENSION_TENSOR=ON      \
         -DEXECUTORCH_BUILD_KERNELS_LLM=ON        \
         -DEXECUTORCH_BUILD_KERNELS_OPTIMIZED=ON     \
diff --git a/.github/workflows/trunk.yml b/.github/workflows/trunk.yml
index 2e5047e6958..7db44e6160a 100644
--- a/.github/workflows/trunk.yml
+++ b/.github/workflows/trunk.yml
@@ -609,7 +609,6 @@ jobs:
           -DEXECUTORCH_ENABLE_LOGGING=1 \
           -DCMAKE_BUILD_TYPE=Release \
           -DEXECUTORCH_BUILD_EXTENSION_DATA_LOADER=ON \
-          -DEXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR=ON \
           -DEXECUTORCH_BUILD_EXTENSION_MODULE=ON \
           -DEXECUTORCH_BUILD_EXTENSION_TENSOR=ON \
           -DEXECUTORCH_BUILD_XNNPACK=ON \
diff --git a/backends/qualcomm/scripts/build.sh b/backends/qualcomm/scripts/build.sh
index 8099ecb3de8..3be09223473 100755
--- a/backends/qualcomm/scripts/build.sh
+++ b/backends/qualcomm/scripts/build.sh
@@ -82,7 +82,6 @@ if [ "$BUILD_AARCH64" = true ]; then
         -DEXECUTORCH_BUILD_DEVTOOLS=ON \
         -DEXECUTORCH_BUILD_EXTENSION_MODULE=ON \
         -DEXECUTORCH_BUILD_EXTENSION_DATA_LOADER=ON \
-        -DEXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR=ON \
         -DEXECUTORCH_BUILD_EXTENSION_TENSOR=ON \
         -DEXECUTORCH_ENABLE_EVENT_TRACER=ON \
         -DQNN_SDK_ROOT=$QNN_SDK_ROOT \
@@ -130,7 +129,6 @@ if [ "$BUILD_X86_64" = true ]; then
         -DEXECUTORCH_BUILD_DEVTOOLS=ON \
         -DEXECUTORCH_BUILD_EXTENSION_MODULE=ON \
         -DEXECUTORCH_BUILD_EXTENSION_DATA_LOADER=ON \
-        -DEXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR=ON \
         -DEXECUTORCH_BUILD_KERNELS_QUANTIZED=ON \
         -DEXECUTORCH_BUILD_EXTENSION_TENSOR=ON \
         -DEXECUTORCH_ENABLE_EVENT_TRACER=ON \
diff --git a/tools/cmake/preset/apple_common.cmake b/tools/cmake/preset/apple_common.cmake
index a14a0932394..516ae5838ab 100644
--- a/tools/cmake/preset/apple_common.cmake
+++ b/tools/cmake/preset/apple_common.cmake
@@ -20,7 +20,6 @@ set_overridable_option(EXECUTORCH_XNNPACK_SHARED_WORKSPACE ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_APPLE ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_DATA_LOADER ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_MODULE ON)
-set_overridable_option(EXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_TENSOR ON)
 set_overridable_option(EXECUTORCH_BUILD_KERNELS_LLM ON)
 set_overridable_option(EXECUTORCH_BUILD_KERNELS_OPTIMIZED ON)
diff --git a/tools/cmake/preset/default.cmake b/tools/cmake/preset/default.cmake
index 7b80e48588c..04fde987255 100644
--- a/tools/cmake/preset/default.cmake
+++ b/tools/cmake/preset/default.cmake
@@ -302,7 +302,6 @@ check_required_options_on(
     EXECUTORCH_BUILD_EXTENSION_MODULE
   REQUIRES
     EXECUTORCH_BUILD_EXTENSION_DATA_LOADER
-    EXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR
 )
 
 check_required_options_on(
diff --git a/tools/cmake/preset/llm.cmake b/tools/cmake/preset/llm.cmake
index 9589e1d8ce2..423892ba171 100644
--- a/tools/cmake/preset/llm.cmake
+++ b/tools/cmake/preset/llm.cmake
@@ -6,7 +6,6 @@
 
 # keep sorted
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_DATA_LOADER ON)
-set_overridable_option(EXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_MODULE ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_TENSOR ON)
 set_overridable_option(EXECUTORCH_BUILD_KERNELS_LLM ON)