diff --git a/doc/source/whatsnew/v1.4.0.rst b/doc/source/whatsnew/v1.4.0.rst
index 0c841078fe9b4..87dd369a8d9aa 100644
--- a/doc/source/whatsnew/v1.4.0.rst
+++ b/doc/source/whatsnew/v1.4.0.rst
@@ -338,6 +338,7 @@ Other Deprecations
 - Deprecated the ``index`` argument to :class:`SparseArray` construction (:issue:`23089`)
 - Deprecated the ``closed`` argument in :meth:`date_range` and :meth:`bdate_range` in favor of ``inclusive`` argument; In a future version passing ``closed`` will raise (:issue:`40245`)
 - Deprecated :meth:`.Rolling.validate`, :meth:`.Expanding.validate`, and :meth:`.ExponentialMovingWindow.validate` (:issue:`43665`)
+- Deprecated the 'include_start' and 'include_end' arguments in :meth:`DatetimeIndex.indexer_between_time`; in a future version passing 'include_start' or 'include_end' will raise (:issue:`43602`)
 - Deprecated silent dropping of columns that raised a ``TypeError`` in :class:`Series.transform` and :class:`DataFrame.transform` when used with a dictionary (:issue:`43740`)
 - Deprecated silent dropping of columns that raised a ``TypeError``, ``DataError``, and some cases of ``ValueError`` in :meth:`Series.aggregate`, :meth:`DataFrame.aggregate`, :meth:`Series.groupby.aggregate`, and :meth:`DataFrame.groupby.aggregate` when used with a list (:issue:`43740`)
 
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index af8c64d5c0202..83b2d76d49169 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -72,7 +72,6 @@
     validate_ascending,
     validate_bool_kwarg,
     validate_fillna_kwargs,
-    validate_inclusive,
 )
 
 from pandas.core.dtypes.common import (
@@ -7832,13 +7831,7 @@ def between_time(
         elif inclusive is None:
             # On arg removal inclusive can default to "both"
             inclusive = "both"
-        left_inclusive, right_inclusive = validate_inclusive(inclusive)
-        indexer = index.indexer_between_time(
-            start_time,
-            end_time,
-            include_start=left_inclusive,
-            include_end=right_inclusive,
-        )
+        indexer = index.indexer_between_time(start_time, end_time, inclusive)
         return self._take_with_is_copy(indexer, axis=axis)
 
     @doc(**_shared_doc_kwargs)
diff --git a/pandas/core/indexes/datetimes.py b/pandas/core/indexes/datetimes.py
index d556466554ea4..dd7f2a08fa939 100644
--- a/pandas/core/indexes/datetimes.py
+++ b/pandas/core/indexes/datetimes.py
@@ -822,7 +822,7 @@ def indexer_at_time(self, time, asof: bool = False) -> npt.NDArray[np.intp]:
         return (time_micros == micros).nonzero()[0]
 
     def indexer_between_time(
-        self, start_time, end_time, include_start: bool = True, include_end: bool = True
+        self, start_time, end_time, inclusive="both"
     ) -> npt.NDArray[np.intp]:
         """
         Return index locations of values between particular times of day
@@ -834,8 +834,8 @@ def indexer_between_time(
             Time passed either as object (datetime.time) or as string in
             appropriate format ("%H:%M", "%H%M", "%I:%M%p", "%I%M%p",
             "%H:%M:%S", "%H%M%S", "%I:%M:%S%p","%I%M%S%p").
-        include_start : bool, default True
-        include_end : bool, default True
+        inclusive : {"both", "neither", "left", "right"}, default "both"
+            Include boundaries; whether to set each bound as closed or open.
 
         Returns
         -------
@@ -852,12 +852,12 @@ def indexer_between_time(
         start_micros = _time_to_micros(start_time)
         end_micros = _time_to_micros(end_time)
 
-        if include_start and include_end:
+        if inclusive == "both":
             lop = rop = operator.le
-        elif include_start:
+        elif inclusive == "left":
             lop = operator.le
             rop = operator.lt
-        elif include_end:
+        elif inclusive == "right":
             lop = operator.lt
             rop = operator.le
         else: