diff --git a/packages/@aws-cdk/toolkit-lib/lib/api/validate/validate-formatting.ts b/packages/@aws-cdk/toolkit-lib/lib/api/validate/validate-formatting.ts
index bf5f032e2..9cf060fb0 100644
--- a/packages/@aws-cdk/toolkit-lib/lib/api/validate/validate-formatting.ts
+++ b/packages/@aws-cdk/toolkit-lib/lib/api/validate/validate-formatting.ts
@@ -40,7 +40,7 @@ function flattenViolations(reports: PluginReportJson[]): FlattenedViolation[] {
     const pluginName = report.pluginName;
     return report.violations.flatMap((violation) => {
       return violation.violatingConstructs.map((construct) => ({
-        severity: normalizeSeverity(violation.severity),
+        severity: normalizeSeverity(violation.severity, violation.customSeverity),
         description: violation.description,
         ruleName: violation.ruleName,
         pluginName,
diff --git a/packages/@aws-cdk/toolkit-lib/test/api/validate/validate-formatting.test.ts b/packages/@aws-cdk/toolkit-lib/test/api/validate/validate-formatting.test.ts
index c70ae4ce5..cb95834b3 100644
--- a/packages/@aws-cdk/toolkit-lib/test/api/validate/validate-formatting.test.ts
+++ b/packages/@aws-cdk/toolkit-lib/test/api/validate/validate-formatting.test.ts
@@ -36,6 +36,24 @@ describe('formatValidateResult', () => {
     ]);
   });
 
+  test('uses the plugin-supplied customSeverity label for a "custom" severity violation', () => {
+    const result = makeResult([{
+      pluginName: 'TestPlugin',
+      conclusion: 'failure',
+      violations: [{
+        ruleName: 'r1',
+        description: 'blocker issue',
+        severity: 'custom',
+        customSeverity: 'BLOCKER',
+        violatingConstructs: [{ constructPath: 'Stack/A' }],
+      }],
+    }]);
+
+    const output = formatValidateResult(result);
+    expect(output).toContain('BLOCKER');
+    expect(output).not.toContain('INFO');
+  });
+
   test('formats construct path with logical id', () => {
     const result = makeResult([{
       pluginName: 'TestPlugin',