diff --git a/script/hassfest/manifest.py b/script/hassfest/manifest.py
index fdbcf5bcb78..6e9cd8bdedc 100644
--- a/script/hassfest/manifest.py
+++ b/script/hassfest/manifest.py
@@ -27,6 +27,8 @@ DOCUMENTATION_URL_HOST = "www.home-assistant.io"
 DOCUMENTATION_URL_PATH_PREFIX = "/integrations/"
 DOCUMENTATION_URL_EXCEPTIONS = {"https://www.home-assistant.io/hassio"}
 
+_CORE_DOCUMENTATION_BASE = "https://www.home-assistant.io/integrations"
+
 
 class NonScaledQualityScaleTiers(StrEnum):
     """Supported manifest quality scales."""
@@ -117,19 +119,26 @@ NO_IOT_CLASS = [
 ]
 
 
-def documentation_url(value: str) -> str:
+def core_documentation_url(value: str) -> str:
     """Validate that a documentation url has the correct path and domain."""
     if value in DOCUMENTATION_URL_EXCEPTIONS:
         return value
+    if not value.startswith(_CORE_DOCUMENTATION_BASE):
+        raise vol.Invalid(
+            f"Documentation URL does not begin with {_CORE_DOCUMENTATION_BASE}"
+        )
 
+    return value
+
+
+def custom_documentation_url(value: str) -> str:
+    """Validate that a custom integration documentation url is correct."""
     parsed_url = urlparse(value)
     if parsed_url.scheme != DOCUMENTATION_URL_SCHEMA:
         raise vol.Invalid("Documentation url is not prefixed with https")
-    if parsed_url.netloc == DOCUMENTATION_URL_HOST and not parsed_url.path.startswith(
-        DOCUMENTATION_URL_PATH_PREFIX
-    ):
+    if value.startswith(_CORE_DOCUMENTATION_BASE):
         raise vol.Invalid(
-            "Documentation url does not begin with www.home-assistant.io/integrations"
+            "Documentation URL should point to the custom integration documentation"
         )
 
     return value
@@ -258,7 +267,7 @@ INTEGRATION_MANIFEST_SCHEMA = vol.Schema(
                 }
             )
         ],
-        vol.Required("documentation"): vol.All(vol.Url(), documentation_url),
+        vol.Required("documentation"): vol.All(vol.Url(), core_documentation_url),
         vol.Optional("quality_scale"): vol.In(SUPPORTED_QUALITY_SCALES),
         vol.Optional("requirements"): [str],
         vol.Optional("dependencies"): [str],
@@ -293,6 +302,7 @@ def manifest_schema(value: dict[str, Any]) -> vol.Schema:
 
 CUSTOM_INTEGRATION_MANIFEST_SCHEMA = INTEGRATION_MANIFEST_SCHEMA.extend(
     {
+        vol.Required("documentation"): vol.All(vol.Url(), custom_documentation_url),
         vol.Optional("version"): vol.All(str, verify_version),
         vol.Optional("issue_tracker"): vol.Url(),
         vol.Optional("import_executor"): bool,