diff --git a/doc/source/whatsnew/v3.0.0.rst b/doc/source/whatsnew/v3.0.0.rst
index 865996bdf8892..a24c32ff213b9 100644
--- a/doc/source/whatsnew/v3.0.0.rst
+++ b/doc/source/whatsnew/v3.0.0.rst
@@ -269,6 +269,7 @@ Other Deprecations
 - Deprecated allowing non-keyword arguments in :meth:`Series.to_markdown` except ``buf``. (:issue:`57280`)
 - Deprecated allowing non-keyword arguments in :meth:`Series.to_string` except ``buf``. (:issue:`57280`)
 - Deprecated behavior of :meth:`Series.dt.to_pytimedelta`, in a future version this will return a :class:`Series` containing python ``datetime.timedelta`` objects instead of an ``ndarray`` of timedelta; this matches the behavior of other :meth:`Series.dt` properties. (:issue:`57463`)
+- Deprecated converting object-dtype columns of ``datetime.datetime`` objects to datetime64 when writing to stata (:issue:`56536`)
 - Deprecated parameter ``method`` in :meth:`DataFrame.reindex_like` / :meth:`Series.reindex_like` (:issue:`58667`)
 - Deprecated using ``epoch`` date format in :meth:`DataFrame.to_json` and :meth:`Series.to_json`, use ``iso`` instead. (:issue:`57063`)
 -
diff --git a/pandas/io/stata.py b/pandas/io/stata.py
index b87ec94b85bb0..64932fe913cf3 100644
--- a/pandas/io/stata.py
+++ b/pandas/io/stata.py
@@ -393,6 +393,14 @@ def parse_dates_safe(
                 d["days"] = np.asarray(diff).astype("m8[D]").view("int64")
 
         elif infer_dtype(dates, skipna=False) == "datetime":
+            warnings.warn(
+                # GH#56536
+                "Converting object-dtype columns of datetimes to datetime64 when "
+                "writing to stata is deprecated. Call "
+                "`df=df.infer_objects(copy=False)` before writing to stata instead.",
+                FutureWarning,
+                stacklevel=find_stack_level(),
+            )
             if delta:
                 delta = dates._values - stata_epoch
 
diff --git a/pandas/tests/io/test_stata.py b/pandas/tests/io/test_stata.py
index d5134a3e3afd0..22fd38ac63483 100644
--- a/pandas/tests/io/test_stata.py
+++ b/pandas/tests/io/test_stata.py
@@ -957,7 +957,12 @@ def test_big_dates(self, datapath, temp_file):
         # {c : c[-2:] for c in columns}
         path = temp_file
         expected.index.name = "index"
-        expected.to_stata(path, convert_dates=date_conversion)
+        msg = (
+            "Converting object-dtype columns of datetimes to datetime64 "
+            "when writing to stata is deprecated"
+        )
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            expected.to_stata(path, convert_dates=date_conversion)
         written_and_read_again = self.read_dta(path)
 
         tm.assert_frame_equal(