BUG: fix to #62205 (#62320)

Author: PluvioXO

pandas/io/json/_normalize.py

@@ -524,7 +524,10 @@ def _pull_records(js: dict[str, Any], spec: list | str) -> list:
             # TODO: handle record value which are lists, at least error
             #       reasonably
             data = nested_to_record(data, sep=sep, max_level=max_level)
-        return DataFrame(data, index=index)
+        result = DataFrame(data, index=index)
+        if record_prefix is not None:
+            result = result.rename(columns=lambda x: f"{record_prefix}{x}")
+        return result
     elif not isinstance(record_path, list):
         record_path = [record_path]
 

pandas/tests/io/json/test_normalize.py

@@ -380,6 +380,19 @@ def test_record_prefix(self, state_data):
 
         tm.assert_frame_equal(result, expected)
 
+    def test_record_prefix_no_record_path_series(self):
+        # Ensure record_prefix is applied when record_path is None for Series input
+        s = Series([{"k": f"{i}", "m": "q"} for i in range(3)])
+        result = json_normalize(s, record_prefix="T.")
+        expected = DataFrame(
+            [
+                {"T.k": "0", "T.m": "q"},
+                {"T.k": "1", "T.m": "q"},
+                {"T.k": "2", "T.m": "q"},
+            ]
+        )
+        tm.assert_frame_equal(result, expected)
+
     def test_non_ascii_key(self):
         testjson = (
             b'[{"\xc3\x9cnic\xc3\xb8de":0,"sub":{"A":1, "B":2}},'