diff --git a/modules/openapi-generator/src/main/resources/python/api_client.mustache b/modules/openapi-generator/src/main/resources/python/api_client.mustache
index e414300cd095..a25eb9bd7188 100644
--- a/modules/openapi-generator/src/main/resources/python/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/python/api_client.mustache
@@ -680,7 +680,13 @@ class ApiClient:
         :param auth_setting: auth settings for the endpoint
         """
         if auth_setting['in'] == 'cookie':
-            headers['Cookie'] = auth_setting['value']
+            if not 'Cookie' in headers:
+                headers['Cookie'] = ""
+            else:
+                headers['Cookie'] += "; "
+            # Encode spaces and semicolons in cookie value, leaving other characters as-is
+            cookie_value = str(auth_setting['value']).replace(" ", "%20").replace(";", "%3B")
+            headers['Cookie'] += f"{auth_setting['key']}={cookie_value}"
         elif auth_setting['in'] == 'header':
             if auth_setting['type'] != 'http-signature':
                 headers[auth_setting['key']] = auth_setting['value']
diff --git a/samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/api_client.py b/samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/api_client.py
index 4b824e431f11..7b2e68094897 100644
--- a/samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/api_client.py
+++ b/samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/api_client.py
@@ -673,7 +673,13 @@ def _apply_auth_params(
         :param auth_setting: auth settings for the endpoint
         """
         if auth_setting['in'] == 'cookie':
-            headers['Cookie'] = auth_setting['value']
+            if not 'Cookie' in headers:
+                headers['Cookie'] = ""
+            else:
+                headers['Cookie'] += "; "
+            # Encode spaces and semicolons in cookie value, leaving other characters as-is
+            cookie_value = str(auth_setting['value']).replace(" ", "%20").replace(";", "%3B")
+            headers['Cookie'] += f"{auth_setting['key']}={cookie_value}"
         elif auth_setting['in'] == 'header':
             if auth_setting['type'] != 'http-signature':
                 headers[auth_setting['key']] = auth_setting['value']
diff --git a/samples/client/echo_api/python/openapi_client/api_client.py b/samples/client/echo_api/python/openapi_client/api_client.py
index 4b824e431f11..7b2e68094897 100644
--- a/samples/client/echo_api/python/openapi_client/api_client.py
+++ b/samples/client/echo_api/python/openapi_client/api_client.py
@@ -673,7 +673,13 @@ def _apply_auth_params(
         :param auth_setting: auth settings for the endpoint
         """
         if auth_setting['in'] == 'cookie':
-            headers['Cookie'] = auth_setting['value']
+            if not 'Cookie' in headers:
+                headers['Cookie'] = ""
+            else:
+                headers['Cookie'] += "; "
+            # Encode spaces and semicolons in cookie value, leaving other characters as-is
+            cookie_value = str(auth_setting['value']).replace(" ", "%20").replace(";", "%3B")
+            headers['Cookie'] += f"{auth_setting['key']}={cookie_value}"
         elif auth_setting['in'] == 'header':
             if auth_setting['type'] != 'http-signature':
                 headers[auth_setting['key']] = auth_setting['value']
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_client.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_client.py
index 3d0170779a39..c2a5838c7e48 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_client.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_client.py
@@ -675,7 +675,13 @@ def _apply_auth_params(
         :param auth_setting: auth settings for the endpoint
         """
         if auth_setting['in'] == 'cookie':
-            headers['Cookie'] = auth_setting['value']
+            if not 'Cookie' in headers:
+                headers['Cookie'] = ""
+            else:
+                headers['Cookie'] += "; "
+            # Encode spaces and semicolons in cookie value, leaving other characters as-is
+            cookie_value = str(auth_setting['value']).replace(" ", "%20").replace(";", "%3B")
+            headers['Cookie'] += f"{auth_setting['key']}={cookie_value}"
         elif auth_setting['in'] == 'header':
             if auth_setting['type'] != 'http-signature':
                 headers[auth_setting['key']] = auth_setting['value']
diff --git a/samples/openapi3/client/petstore/python-httpx-sync/petstore_api/api_client.py b/samples/openapi3/client/petstore/python-httpx-sync/petstore_api/api_client.py
index 3d0170779a39..c2a5838c7e48 100644
--- a/samples/openapi3/client/petstore/python-httpx-sync/petstore_api/api_client.py
+++ b/samples/openapi3/client/petstore/python-httpx-sync/petstore_api/api_client.py
@@ -675,7 +675,13 @@ def _apply_auth_params(
         :param auth_setting: auth settings for the endpoint
         """
         if auth_setting['in'] == 'cookie':
-            headers['Cookie'] = auth_setting['value']
+            if not 'Cookie' in headers:
+                headers['Cookie'] = ""
+            else:
+                headers['Cookie'] += "; "
+            # Encode spaces and semicolons in cookie value, leaving other characters as-is
+            cookie_value = str(auth_setting['value']).replace(" ", "%20").replace(";", "%3B")
+            headers['Cookie'] += f"{auth_setting['key']}={cookie_value}"
         elif auth_setting['in'] == 'header':
             if auth_setting['type'] != 'http-signature':
                 headers[auth_setting['key']] = auth_setting['value']
diff --git a/samples/openapi3/client/petstore/python-httpx/petstore_api/api_client.py b/samples/openapi3/client/petstore/python-httpx/petstore_api/api_client.py
index 3d0170779a39..c2a5838c7e48 100644
--- a/samples/openapi3/client/petstore/python-httpx/petstore_api/api_client.py
+++ b/samples/openapi3/client/petstore/python-httpx/petstore_api/api_client.py
@@ -675,7 +675,13 @@ def _apply_auth_params(
         :param auth_setting: auth settings for the endpoint
         """
         if auth_setting['in'] == 'cookie':
-            headers['Cookie'] = auth_setting['value']
+            if not 'Cookie' in headers:
+                headers['Cookie'] = ""
+            else:
+                headers['Cookie'] += "; "
+            # Encode spaces and semicolons in cookie value, leaving other characters as-is
+            cookie_value = str(auth_setting['value']).replace(" ", "%20").replace(";", "%3B")
+            headers['Cookie'] += f"{auth_setting['key']}={cookie_value}"
         elif auth_setting['in'] == 'header':
             if auth_setting['type'] != 'http-signature':
                 headers[auth_setting['key']] = auth_setting['value']
diff --git a/samples/openapi3/client/petstore/python-lazyImports/petstore_api/api_client.py b/samples/openapi3/client/petstore/python-lazyImports/petstore_api/api_client.py
index d388566cbbe2..279b5199af21 100644
--- a/samples/openapi3/client/petstore/python-lazyImports/petstore_api/api_client.py
+++ b/samples/openapi3/client/petstore/python-lazyImports/petstore_api/api_client.py
@@ -672,7 +672,13 @@ def _apply_auth_params(
         :param auth_setting: auth settings for the endpoint
         """
         if auth_setting['in'] == 'cookie':
-            headers['Cookie'] = auth_setting['value']
+            if not 'Cookie' in headers:
+                headers['Cookie'] = ""
+            else:
+                headers['Cookie'] += "; "
+            # Encode spaces and semicolons in cookie value, leaving other characters as-is
+            cookie_value = str(auth_setting['value']).replace(" ", "%20").replace(";", "%3B")
+            headers['Cookie'] += f"{auth_setting['key']}={cookie_value}"
         elif auth_setting['in'] == 'header':
             if auth_setting['type'] != 'http-signature':
                 headers[auth_setting['key']] = auth_setting['value']
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api_client.py b/samples/openapi3/client/petstore/python/petstore_api/api_client.py
index d388566cbbe2..279b5199af21 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/api_client.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api_client.py
@@ -672,7 +672,13 @@ def _apply_auth_params(
         :param auth_setting: auth settings for the endpoint
         """
         if auth_setting['in'] == 'cookie':
-            headers['Cookie'] = auth_setting['value']
+            if not 'Cookie' in headers:
+                headers['Cookie'] = ""
+            else:
+                headers['Cookie'] += "; "
+            # Encode spaces and semicolons in cookie value, leaving other characters as-is
+            cookie_value = str(auth_setting['value']).replace(" ", "%20").replace(";", "%3B")
+            headers['Cookie'] += f"{auth_setting['key']}={cookie_value}"
         elif auth_setting['in'] == 'header':
             if auth_setting['type'] != 'http-signature':
                 headers[auth_setting['key']] = auth_setting['value']