diff --git a/.changeset/green-vans-peel.md b/.changeset/green-vans-peel.md
new file mode 100644
index 0000000000..cd4d30139a
--- /dev/null
+++ b/.changeset/green-vans-peel.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-catalog-react': patch
+---
+
+Fix `EntityTypeFilter` so it produces unique case-insensitive set of available types
diff --git a/plugins/catalog-react/src/hooks/useEntityTypeFilter.tsx b/plugins/catalog-react/src/hooks/useEntityTypeFilter.tsx
index 068e995522..5fa6b0f1a2 100644
--- a/plugins/catalog-react/src/hooks/useEntityTypeFilter.tsx
+++ b/plugins/catalog-react/src/hooks/useEntityTypeFilter.tsx
@@ -86,10 +86,11 @@ export function useEntityTypeFilter(): EntityTypeReturn {
     const countByType = entities.reduce((acc, entity) => {
       if (typeof entity.spec?.type !== 'string') return acc;
 
-      if (!acc[entity.spec.type]) {
-        acc[entity.spec.type] = 0;
+      const entityType = entity.spec.type.toLocaleLowerCase('en-US');
+      if (!acc[entityType]) {
+        acc[entityType] = 0;
       }
-      acc[entity.spec.type] += 1;
+      acc[entityType] += 1;
       return acc;
     }, {} as Record<string, number>);