diff --git a/awscli/botocore/regions.py b/awscli/botocore/regions.py
index 0c384ac7c009..32367ef8dcc3 100644
--- a/awscli/botocore/regions.py
+++ b/awscli/botocore/regions.py
@@ -514,7 +514,11 @@ def construct_endpoint(
         LOG.debug(f'Endpoint provider result: {provider_result.url}')
 
         # The endpoint provider does not support non-secure transport.
-        if not self._use_ssl and provider_result.url.startswith('https://'):
+        if (
+                not self._use_ssl
+                and provider_result.url.startswith('https://')
+                and 'Endpoint' not in provider_params
+        ):
             provider_result = provider_result._replace(
                 url=f'http://{provider_result.url[8:]}'
             )
diff --git a/tests/unit/botocore/test_endpoint_provider.py b/tests/unit/botocore/test_endpoint_provider.py
index 345c71ebe727..747264aabb8f 100644
--- a/tests/unit/botocore/test_endpoint_provider.py
+++ b/tests/unit/botocore/test_endpoint_provider.py
@@ -16,6 +16,7 @@
 import os
 
 import pytest
+
 from botocore.endpoint_provider import (
     EndpointProvider,
     EndpointRule,
@@ -23,7 +24,7 @@
     RuleCreator,
     RuleSet,
     RuleSetStandardLibary,
-    TreeRule,
+    TreeRule, RuleSetEndpoint,
 )
 from botocore.exceptions import (
     EndpointResolutionError,
@@ -32,6 +33,8 @@
 from botocore.loaders import Loader
 from botocore.regions import EndpointRulesetResolver
 
+from unittest.mock import Mock, patch
+
 REGION_TEMPLATE = "{Region}"
 REGION_REF = {"ref": "Region"}
 BUCKET_ARN_REF = {"ref": "bucketArn"}
@@ -486,3 +489,77 @@ def test_auth_schemes_conversion_first_authtype_unknown(
 def test_get_attr(rule_lib, value, path, expected_value):
     result = rule_lib.get_attr(value, path)
     assert result == expected_value
+@pytest.mark.parametrize(
+    "use_ssl, endpoint_url, provider_params, expected_url",
+    [
+        # use_ssl=True, endpoint_url="http://..." → HTTP
+        (
+            True,
+            'http://custom.com',
+            {'Endpoint': 'http://custom.com'},
+            'http://custom.com',
+        ),
+        # use_ssl=True, endpoint_url="https://..." → HTTPS
+        (
+            True,
+            'https://custom.com',
+            {'Endpoint': 'https://custom.com'},
+            'https://custom.com',
+        ),
+        # use_ssl=False, endpoint_url="http://..." → HTTP
+        (
+            False,
+            'http://custom.com',
+            {'Endpoint': 'http://custom.com'},
+            'http://custom.com',
+        ),
+        # use_ssl=False, endpoint_url="https://..." → HTTPS
+        (
+            False,
+            'https://custom.com',
+            {'Endpoint': 'https://custom.com'},
+            'https://custom.com',
+        ),
+        # use_ssl=True, no endpoint → HTTPS
+        (
+            True,
+            'https://s3-test-only-domain.amazonaws.com',
+            {},
+            'https://s3-test-only-domain.amazonaws.com',
+        ),
+        # use_ssl=False, no endpoint → HTTP (downgrade)
+        (
+            False,
+            'https://s3-test-only-domain.amazonaws.com',
+            {},
+            'http://s3-test-only-domain.amazonaws.com',
+        ),
+    ],
+)
+def test_construct_endpoint_parametrized(
+    use_ssl, endpoint_url, provider_params, expected_url
+):
+    resolver = EndpointRulesetResolver(
+        endpoint_ruleset_data={
+            'version': '1.0',
+            'parameters': {},
+            'rules': [],
+        },
+        partition_data={},
+        service_model=None,
+        builtins={},
+        client_context=None,
+        event_emitter=None,
+        use_ssl=use_ssl,
+        requested_auth_scheme=None,
+    )
+
+    with patch.object(resolver._provider, 'resolve_endpoint') as mock_resolve:
+        mock_resolve.return_value = RuleSetEndpoint(
+            url=endpoint_url, properties={}, headers={}
+        )
+        with patch.object(
+            resolver, '_get_provider_params', return_value=provider_params
+        ):
+            result = resolver.construct_endpoint(None, None, None)
+            assert result.url == expected_url
\ No newline at end of file