diff --git a/independent-projects/tools/devtools-common/src/main/java/io/quarkus/platform/catalog/processor/CatalogProcessor.java b/independent-projects/tools/devtools-common/src/main/java/io/quarkus/platform/catalog/processor/CatalogProcessor.java
index 4905ade770495..8fbd392efdce0 100644
--- a/independent-projects/tools/devtools-common/src/main/java/io/quarkus/platform/catalog/processor/CatalogProcessor.java
+++ b/independent-projects/tools/devtools-common/src/main/java/io/quarkus/platform/catalog/processor/CatalogProcessor.java
@@ -3,6 +3,7 @@
 import static io.quarkus.platform.catalog.processor.ExtensionProcessor.isUnlisted;
 
 import java.util.*;
+import java.util.stream.Collectors;
 
 import io.quarkus.registry.catalog.Category;
 import io.quarkus.registry.catalog.Extension;
@@ -32,8 +33,12 @@ public static CatalogProcessor of(ExtensionCatalog catalog) {
 
     public static List<ProcessedCategory> getProcessedCategoriesInOrder(ExtensionCatalog catalog) {
         final Map<String, List<Extension>> extsByCategory = new HashMap<>(catalog.getCategories().size());
+        final Set<String> availableCategories = catalog.getCategories().stream().map(Category::getId)
+                .collect(Collectors.toSet());
         for (Extension e : catalog.getExtensions()) {
-            List<String> categories = new ArrayList<>(ExtensionProcessor.of(e).getCategories());
+            List<String> categories = ExtensionProcessor.of(e).getCategories().stream()
+                    .filter(availableCategories::contains)
+                    .collect(Collectors.toCollection(ArrayList::new));
             if (!isUnlisted(e)) {
                 if (categories.isEmpty()) {
                     categories.add(UNCATEGORIZED_CATEGORY.getId());
diff --git a/independent-projects/tools/devtools-testing/src/main/resources/fake-catalog.json b/independent-projects/tools/devtools-testing/src/main/resources/fake-catalog.json
index a98dad34954a2..5305537560a1c 100644
--- a/independent-projects/tools/devtools-testing/src/main/resources/fake-catalog.json
+++ b/independent-projects/tools/devtools-testing/src/main/resources/fake-catalog.json
@@ -220,6 +220,9 @@
         "keywords": [
           "uncategorized"
         ],
+        "categories": [
+          "unknown"
+        ],
         "status": "preview",
         "built-with-quarkus-core": "999-FAKE"
       },
@@ -227,6 +230,21 @@
       "origins": [
         "io.quarkus:quarkus-fake-bom:999-FAKE:json:999-FAKE"
       ]
+    },
+    {
+      "name": "extension in unknown category",
+      "description": "Some unknown category extension",
+      "metadata": {
+        "keywords": [
+          "unknown-category"
+        ],
+        "status": "preview",
+        "built-with-quarkus-core": "999-FAKE"
+      },
+      "artifact": "io.quarkus:quarkus-unknown-category-extension::jar:999-FAKE",
+      "origins": [
+        "io.quarkus:quarkus-fake-bom:999-FAKE:json:999-FAKE"
+      ]
     }
   ],
   "categories": [
diff --git a/integration-tests/devtools/src/test/java/io/quarkus/platform/catalog/CatalogProcessorTest.java b/integration-tests/devtools/src/test/java/io/quarkus/platform/catalog/CatalogProcessorTest.java
index eaf3677d2a46d..0b7f884660c55 100644
--- a/integration-tests/devtools/src/test/java/io/quarkus/platform/catalog/CatalogProcessorTest.java
+++ b/integration-tests/devtools/src/test/java/io/quarkus/platform/catalog/CatalogProcessorTest.java
@@ -46,6 +46,6 @@ void testUncategorizedExtensions() {
         assertThat(uncategorized.get().getSortedExtensions())
                 .map(Extension::getArtifact)
                 .map(ArtifactCoords::getArtifactId)
-                .contains("quarkus-uncategorized-extension");
+                .containsExactlyInAnyOrder("quarkus-unknown-category-extension", "quarkus-uncategorized-extension");
     }
 }