diff --git a/lib/modules/manager/kustomize/extract.spec.ts b/lib/modules/manager/kustomize/extract.spec.ts
index c22b7628fc88dbe73697efa588418aaf2cc0c167..29c11bf5ef750c26e1f0075cc707c7604f358b21 100644
--- a/lib/modules/manager/kustomize/extract.spec.ts
+++ b/lib/modules/manager/kustomize/extract.spec.ts
@@ -34,6 +34,22 @@ describe('modules/manager/kustomize/extract', () => {
     const file = parseKustomize('');
     expect(file).toBeNull();
   });
+  it('should return null when header has invalid resource kind', () => {
+    const file = parseKustomize(`
+      kind: NoKustomization
+      bases:
+      - github.com/fluxcd/flux/deploy?ref=1.19.0
+    `);
+    expect(file).toBeNull();
+  });
+  it('should fall back to default resource kind when header is missing', () => {
+    const file = parseKustomize(`
+      bases:
+      - github.com/fluxcd/flux/deploy?ref=1.19.0
+    `);
+    expect(file).not.toBeNull();
+    expect(file.kind).toBe('Kustomization');
+  });
   describe('extractBase', () => {
     it('should return null for a local base', () => {
       const res = extractResource('./service-1');
diff --git a/lib/modules/manager/kustomize/extract.ts b/lib/modules/manager/kustomize/extract.ts
index f5de3178f02b4140537c66a3281ee4818c200fdf..469bcc6a0a44af8d3f4c9b923034f69da3500435 100644
--- a/lib/modules/manager/kustomize/extract.ts
+++ b/lib/modules/manager/kustomize/extract.ts
@@ -133,6 +133,8 @@ export function parseKustomize(content: string): Kustomize | null {
     return null;
   }
 
+  pkg.kind ??= 'Kustomization';
+
   if (!['Kustomization', 'Component'].includes(pkg.kind)) {
     return null;
   }
diff --git a/lib/modules/manager/kustomize/readme.md b/lib/modules/manager/kustomize/readme.md
index 723b2cfa999677dfec9621f9716d2c19238099ab..47185687d332f3c696baf5e7a18f9bfbb086e1a2 100644
--- a/lib/modules/manager/kustomize/readme.md
+++ b/lib/modules/manager/kustomize/readme.md
@@ -21,7 +21,6 @@ This manager uses three `depType`s to allow a fine-grained control of which depe
 
 **Limitations**
 
-- Needs to have `kind: Kustomization` or `kind: Component` defined
 - Currently this hasn't been tested using HTTPS to fetch the repos
 - The keys for the image tags can be in any order
 
diff --git a/lib/modules/manager/kustomize/types.ts b/lib/modules/manager/kustomize/types.ts
index 22e0ef573850e4ae7b1bbb9f2cb0149b55a97b9b..c42207daf51c8b3c522c7ce1fc084672a6ff2ca8 100644
--- a/lib/modules/manager/kustomize/types.ts
+++ b/lib/modules/manager/kustomize/types.ts
@@ -12,7 +12,7 @@ export interface HelmChart {
 }
 
 export interface Kustomize {
-  kind: string;
+  kind?: string;
   bases?: string[]; // deprecated since kustomize v2.1.0
   resources?: string[];
   components?: string[];