diff --git a/app/models/project_services/kubernetes_service.rb b/app/models/project_services/kubernetes_service.rb
index 8ba07173c74..45a544e3674 100644
--- a/app/models/project_services/kubernetes_service.rb
+++ b/app/models/project_services/kubernetes_service.rb
@@ -153,7 +153,17 @@ class KubernetesService < DeploymentService
   end
 
   def default_namespace
-    "#{project.path}-#{project.id}" if project.present?
+    return unless project
+
+    # 1. lowercase
+    # 2. replace non kubernetes characters with dash
+    # 3. trim dash from the beginning and end
+
+    slugified = "#{project.path}-#{project.id}"
+    slugified.downcase!
+    slugified.gsub!(/[^a-z0-9]/, '-')
+    slugified.gsub!(/^-+|-+$/, '')
+    slugified
   end
 
   def build_kubeclient!(api_path: 'api', api_version: 'v1')
diff --git a/changelogs/unreleased/mr-14642.yml b/changelogs/unreleased/mr-14642.yml
new file mode 100644
index 00000000000..048cc79e323
--- /dev/null
+++ b/changelogs/unreleased/mr-14642.yml
@@ -0,0 +1,6 @@
+---
+title: Auto Devops kubernetes default namespace is now correctly built out of gitlab
+  project group-name
+merge_request: 14642
+author: Mircea Danila Dumitrescu
+type: fixed