diff --git a/pandas/_libs/tslibs/conversion.pxd b/pandas/_libs/tslibs/conversion.pxd
index d4ae3fa8c5b99..c74307a3d2887 100644
--- a/pandas/_libs/tslibs/conversion.pxd
+++ b/pandas/_libs/tslibs/conversion.pxd
@@ -23,6 +23,4 @@ cdef _TSObject convert_datetime_to_tsobject(datetime ts, object tz,
 
 cdef int64_t get_datetime64_nanos(object val) except? -1
 
-cpdef int64_t pydt_to_i8(object pydt) except? -1
-
 cpdef datetime localize_pydatetime(datetime dt, object tz)
diff --git a/pandas/_libs/tslibs/conversion.pyx b/pandas/_libs/tslibs/conversion.pyx
index 77f46016ee846..e0862b9250045 100644
--- a/pandas/_libs/tslibs/conversion.pyx
+++ b/pandas/_libs/tslibs/conversion.pyx
@@ -223,27 +223,6 @@ cdef class _TSObject:
         return self.value
 
 
-cpdef int64_t pydt_to_i8(object pydt) except? -1:
-    """
-    Convert to int64 representation compatible with numpy datetime64; converts
-    to UTC
-
-    Parameters
-    ----------
-    pydt : object
-
-    Returns
-    -------
-    i8value : np.int64
-    """
-    cdef:
-        _TSObject ts
-
-    ts = convert_to_tsobject(pydt, None, None, 0, 0)
-
-    return ts.value
-
-
 cdef convert_to_tsobject(object ts, object tz, object unit,
                          bint dayfirst, bint yearfirst, int32_t nanos=0):
     """
diff --git a/pandas/_libs/tslibs/offsets.pyx b/pandas/_libs/tslibs/offsets.pyx
index 31dc2945f0395..48a3886c20a3a 100644
--- a/pandas/_libs/tslibs/offsets.pyx
+++ b/pandas/_libs/tslibs/offsets.pyx
@@ -22,7 +22,10 @@ from pandas._libs.tslibs.util cimport is_integer_object
 
 from pandas._libs.tslibs.ccalendar import MONTHS, DAYS
 from pandas._libs.tslibs.ccalendar cimport get_days_in_month, dayofweek
-from pandas._libs.tslibs.conversion cimport pydt_to_i8, localize_pydatetime
+from pandas._libs.tslibs.conversion cimport (
+    convert_datetime_to_tsobject,
+    localize_pydatetime,
+)
 from pandas._libs.tslibs.nattype cimport NPY_NAT
 from pandas._libs.tslibs.np_datetime cimport (
     npy_datetimestruct, dtstruct_to_dt64, dt64_to_dtstruct)
@@ -233,7 +236,10 @@ def _to_dt64D(dt):
     # numpy.datetime64('2013-05-01T02:00:00.000000+0200')
     # Thus astype is needed to cast datetime to datetime64[D]
     if getattr(dt, 'tzinfo', None) is not None:
-        i8 = pydt_to_i8(dt)
+        # Get the nanosecond timestamp,
+        #  equiv `Timestamp(dt).value` or `dt.timestamp() * 10**9`
+        nanos = getattr(dt, "nanosecond", 0)
+        i8 = convert_datetime_to_tsobject(dt, tz=None, nanos=nanos).value
         dt = tz_convert_single(i8, UTC, dt.tzinfo)
         dt = np.int64(dt).astype('datetime64[ns]')
     else:
diff --git a/pandas/tests/scalar/timestamp/test_timestamp.py b/pandas/tests/scalar/timestamp/test_timestamp.py
index c60406fdbc8a6..410e449656dbc 100644
--- a/pandas/tests/scalar/timestamp/test_timestamp.py
+++ b/pandas/tests/scalar/timestamp/test_timestamp.py
@@ -12,7 +12,6 @@
 import pytz
 from pytz import timezone, utc
 
-from pandas._libs.tslibs import conversion
 from pandas._libs.tslibs.timezones import dateutil_gettz as gettz, get_timezone
 import pandas.compat as compat
 from pandas.compat.numpy import np_datetime64_compat
@@ -241,24 +240,20 @@ def test_constructor(self):
             for result in [Timestamp(date_str), Timestamp(date)]:
                 # only with timestring
                 assert result.value == expected
-                assert conversion.pydt_to_i8(result) == expected
 
                 # re-creation shouldn't affect to internal value
                 result = Timestamp(result)
                 assert result.value == expected
-                assert conversion.pydt_to_i8(result) == expected
 
             # with timezone
             for tz, offset in timezones:
                 for result in [Timestamp(date_str, tz=tz), Timestamp(date, tz=tz)]:
                     expected_tz = expected - offset * 3600 * 1_000_000_000
                     assert result.value == expected_tz
-                    assert conversion.pydt_to_i8(result) == expected_tz
 
                     # should preserve tz
                     result = Timestamp(result)
                     assert result.value == expected_tz
-                    assert conversion.pydt_to_i8(result) == expected_tz
 
                     # should convert to UTC
                     if tz is not None:
@@ -267,7 +262,6 @@ def test_constructor(self):
                         result = Timestamp(result, tz="UTC")
                     expected_utc = expected - offset * 3600 * 1_000_000_000
                     assert result.value == expected_utc
-                    assert conversion.pydt_to_i8(result) == expected_utc
 
     def test_constructor_with_stringoffset(self):
         # GH 7833
@@ -300,30 +294,25 @@ def test_constructor_with_stringoffset(self):
             for result in [Timestamp(date_str)]:
                 # only with timestring
                 assert result.value == expected
-                assert conversion.pydt_to_i8(result) == expected
 
                 # re-creation shouldn't affect to internal value
                 result = Timestamp(result)
                 assert result.value == expected
-                assert conversion.pydt_to_i8(result) == expected
 
             # with timezone
             for tz, offset in timezones:
                 result = Timestamp(date_str, tz=tz)
                 expected_tz = expected
                 assert result.value == expected_tz
-                assert conversion.pydt_to_i8(result) == expected_tz
 
                 # should preserve tz
                 result = Timestamp(result)
                 assert result.value == expected_tz
-                assert conversion.pydt_to_i8(result) == expected_tz
 
                 # should convert to UTC
                 result = Timestamp(result).tz_convert("UTC")
                 expected_utc = expected
                 assert result.value == expected_utc
-                assert conversion.pydt_to_i8(result) == expected_utc
 
         # This should be 2013-11-01 05:00 in UTC
         # converted to Chicago tz