diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index 80f9c76e9..21efbed8a 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -445,7 +445,7 @@ def analyze_param(
         )
         field_info = value
         if isinstance(field_info, FieldInfo):
-            field_info.annotation = type_annotation
+            field_info.annotation = use_annotation
 
     # Get Depends from type annotation
     if depends is not None and depends.dependency is None:
diff --git a/tests/test_json_form_syntaxes.py b/tests/test_json_form_syntaxes.py
new file mode 100644
index 000000000..e646136b6
--- /dev/null
+++ b/tests/test_json_form_syntaxes.py
@@ -0,0 +1,135 @@
+import json
+from typing import Annotated, Any
+
+from fastapi import FastAPI, Form, Query
+from fastapi.testclient import TestClient
+from pydantic import Json
+
+app = FastAPI()
+
+
+@app.post("/form-json-equals-syntax")
+def form_json_equals_syntax(data: Json[dict[str, Any]] = Form()) -> dict[str, Any]:
+    return data
+
+
+@app.post("/form-json-annotated-syntax")
+def form_json_annotated_syntax(
+    data: Annotated[Json[dict[str, Any]], Form()],
+) -> dict[str, Any]:
+    return data
+
+
+@app.post("/form-json-list-equals")
+def form_json_list_equals(items: Json[list[str]] = Form()) -> list[str]:
+    return items
+
+
+@app.post("/form-json-list-annotated")
+def form_json_list_annotated(
+    items: Annotated[Json[list[str]], Form()],
+) -> list[str]:
+    return items
+
+
+@app.post("/form-json-nested-equals")
+def form_json_nested_equals(
+    config: Json[dict[str, list[int]]] = Form(),
+) -> dict[str, list[int]]:
+    return config
+
+
+@app.post("/form-json-nested-annotated")
+def form_json_nested_annotated(
+    config: Annotated[Json[dict[str, list[int]]], Form()],
+) -> dict[str, list[int]]:
+    return config
+
+
+client = TestClient(app)
+
+
+def test_form_json_equals_syntax():
+    test_data = {"key": "value", "nested": {"inner": 123}}
+    response = client.post(
+        "/form-json-equals-syntax", data={"data": json.dumps(test_data)}
+    )
+    assert response.status_code == 200, response.text
+    assert response.json() == test_data
+
+
+def test_form_json_annotated_syntax():
+    test_data = {"key": "value", "nested": {"inner": 123}}
+    response = client.post(
+        "/form-json-annotated-syntax", data={"data": json.dumps(test_data)}
+    )
+    assert response.status_code == 200, response.text
+    assert response.json() == test_data
+
+
+def test_form_json_list_equals():
+    test_data = ["abc", "def", "ghi"]
+    response = client.post(
+        "/form-json-list-equals", data={"items": json.dumps(test_data)}
+    )
+    assert response.status_code == 200, response.text
+    assert response.json() == test_data
+
+
+def test_form_json_list_annotated():
+    test_data = ["abc", "def", "ghi"]
+    response = client.post(
+        "/form-json-list-annotated", data={"items": json.dumps(test_data)}
+    )
+    assert response.status_code == 200, response.text
+    assert response.json() == test_data
+
+
+def test_form_json_nested_equals():
+    test_data = {"groups": [1, 2, 3], "ids": [4, 5]}
+    response = client.post(
+        "/form-json-nested-equals", data={"config": json.dumps(test_data)}
+    )
+    assert response.status_code == 200, response.text
+    assert response.json() == test_data
+
+
+def test_form_json_nested_annotated():
+    test_data = {"groups": [1, 2, 3], "ids": [4, 5]}
+    response = client.post(
+        "/form-json-nested-annotated", data={"config": json.dumps(test_data)}
+    )
+    assert response.status_code == 200, response.text
+    assert response.json() == test_data
+
+
+def test_form_json_invalid_json_equals():
+    response = client.post(
+        "/form-json-equals-syntax", data={"data": "not valid json{"}
+    )
+    assert response.status_code == 422
+
+
+def test_form_json_invalid_json_annotated():
+    response = client.post(
+        "/form-json-annotated-syntax", data={"data": "not valid json{"}
+    )
+    assert response.status_code == 422
+
+
+def test_form_json_empty_dict_equals():
+    test_data = {}
+    response = client.post(
+        "/form-json-equals-syntax", data={"data": json.dumps(test_data)}
+    )
+    assert response.status_code == 200, response.text
+    assert response.json() == test_data
+
+
+def test_form_json_empty_list_equals():
+    test_data = []
+    response = client.post(
+        "/form-json-list-equals", data={"items": json.dumps(test_data)}
+    )
+    assert response.status_code == 200, response.text
+    assert response.json() == test_data