diff --git a/app/helpers/webpack_helper.rb b/app/helpers/webpack_helper.rb
index 0386df223741901d61aad057e660eb0f9b4d99f3..33453dd178ff46757e16252efec832ecb4822901 100644
--- a/app/helpers/webpack_helper.rb
+++ b/app/helpers/webpack_helper.rb
@@ -34,6 +34,8 @@ def webpack_public_host
   end
 
   def webpack_public_path
-    "#{webpack_public_host}/#{Rails.application.config.webpack.public_path}/"
+    relative_path = Rails.application.config.relative_url_root
+    webpack_path = Rails.application.config.webpack.public_path
+    File.join(webpack_public_host.to_s, relative_path.to_s, webpack_path.to_s, '')
   end
 end
diff --git a/changelogs/unreleased/35567-fix-relative-urls-in-webpack-public-path.yml b/changelogs/unreleased/35567-fix-relative-urls-in-webpack-public-path.yml
new file mode 100644
index 0000000000000000000000000000000000000000..41b506681f92e97a77f87c538ae94653a73ccd20
--- /dev/null
+++ b/changelogs/unreleased/35567-fix-relative-urls-in-webpack-public-path.yml
@@ -0,0 +1,5 @@
+---
+title: Fix asynchronous javascript paths when GitLab is installed under a relative
+  URL
+merge_request: 13165
+author: