diff --git a/lib/core/custom-theme/README.md b/lib/core/custom-theme/README.md
new file mode 100644
index 0000000000..d145bb275a
--- /dev/null
+++ b/lib/core/custom-theme/README.md
@@ -0,0 +1,3 @@
+# DEPRECATION WARNING
+
+The custom theme is deprecated and will be removed in the future. To generate a custom theme, please refer to the Angular Material [Custom Theme section](https://v18.material.angular.dev/guide/theming#custom-theme).