diff --git a/docs/reference/settings.md b/docs/reference/settings.md
index e5ef3fe10d..f56bcd617c 100644
--- a/docs/reference/settings.md
+++ b/docs/reference/settings.md
@@ -24,10 +24,6 @@ This is the base URL used by the Wagtail admin site. It is typically used for ge
 
 If this setting is not present, Wagtail will try to fall back to `request.site.root_url` or to the request's host name.
 
-```{versionchanged} 3.0
-This setting was previously named ``BASE_URL`` and was undocumented, using ``BASE_URL`` will be removed in a future release.
-```
-
 (append_slash)=
 
 ## Append Slash
diff --git a/wagtail/admin/utils.py b/wagtail/admin/utils.py
index 974abf8a82..315e984ea8 100644
--- a/wagtail/admin/utils.py
+++ b/wagtail/admin/utils.py
@@ -1,26 +1,12 @@
-from warnings import warn
-
 from django.conf import settings
 from django.utils.http import url_has_allowed_host_and_scheme
 
-from wagtail.utils.deprecation import RemovedInWagtail50Warning
-
 
 def get_admin_base_url():
     """
-    Gets the base URL for the wagtail admin site. This is set in `settings.WAGTAILADMIN_BASE_URL`,
-    which was previously `settings.BASE_URL`.
+    Gets the base URL for the wagtail admin site. This is set in `settings.WAGTAILADMIN_BASE_URL`.
     """
-
-    admin_base_url = getattr(settings, "WAGTAILADMIN_BASE_URL", None)
-    if admin_base_url is None and hasattr(settings, "BASE_URL"):
-        warn(
-            "settings.BASE_URL has been renamed to settings.WAGTAILADMIN_BASE_URL",
-            category=RemovedInWagtail50Warning,
-        )
-        admin_base_url = settings.BASE_URL
-
-    return admin_base_url
+    return getattr(settings, "WAGTAILADMIN_BASE_URL", None)
 
 
 def get_valid_next_url_from_request(request):