diff --git a/packages/aws-cdk/lib/cli/util/check-unknown-options.ts b/packages/aws-cdk/lib/cli/util/check-unknown-options.ts
index dc86eb1f8..261ad4514 100644
--- a/packages/aws-cdk/lib/cli/util/check-unknown-options.ts
+++ b/packages/aws-cdk/lib/cli/util/check-unknown-options.ts
@@ -30,6 +30,16 @@ function collectKnownOptions(optionDefs: Record<string, any>): Set<string> {
 /** Pre-computed set of known global options (static, doesn't depend on argv) */
 const globalKnownOptions = collectKnownOptions(config.globalOptions);
 
+/** Reverse mapping from command alias to canonical command name */
+const commandAliasMap = new Map<string, string>();
+for (const [name, def] of Object.entries<any>(config.commands)) {
+  if (def.aliases) {
+    for (const alias of def.aliases) {
+      commandAliasMap.set(alias, name);
+    }
+  }
+}
+
 /** yargs internal keys that are always present in argv */
 const yargsInternals = new Set(['_', '$0', 'help', 'h', 'version']);
 
@@ -43,20 +53,24 @@ const yargsInternals = new Set(['_', '$0', 'help', 'h', 'version']);
  */
 export function findUnknownOptions(argv: any): string[] {
   const command = argv._[0];
+  const canonicalCommand = commandAliasMap.get(command) ?? command;
 
-  const commandDef = config.commands[command];
+  const commandDef = config.commands[canonicalCommand];
   const commandKnownOptions = commandDef?.options
     ? collectKnownOptions(commandDef.options)
     : new Set<string>();
 
-  const positionalArg = commandDef?.arg?.name;
+  const positionalArgRaw = commandDef?.arg?.name;
+  const positionalArgs = positionalArgRaw
+    ? new Set([positionalArgRaw, positionalArgRaw.toLowerCase()])
+    : new Set<string>();
 
   const unknown: string[] = [];
   for (const key of Object.keys(argv)) {
     if (argv[key] === undefined) {
       continue;
     }
-    if (yargsInternals.has(key) || key === positionalArg) {
+    if (yargsInternals.has(key) || positionalArgs.has(key)) {
       continue;
     }
     if (globalKnownOptions.has(key) || commandKnownOptions.has(key)) {
diff --git a/packages/aws-cdk/test/cli/util/check-unknown-options.test.ts b/packages/aws-cdk/test/cli/util/check-unknown-options.test.ts
index b00c01c66..10f6926a9 100644
--- a/packages/aws-cdk/test/cli/util/check-unknown-options.test.ts
+++ b/packages/aws-cdk/test/cli/util/check-unknown-options.test.ts
@@ -93,6 +93,39 @@ describe('findUnknownOptions', () => {
     }
   });
 
+  test('resolves command aliases to canonical names (e.g. ls -> list)', () => {
+    const argv = {
+      '_': ['ls'],
+      '$0': 'cdk',
+      'long': true,
+      'l': true,
+      'showDependencies': false,
+      'show-dependencies': false,
+      'd': false,
+    };
+    expect(findUnknownOptions(argv)).toEqual([]);
+  });
+
+  test('does not report positional args (both original case and lowercase)', () => {
+    const argv = {
+      _: ['ack'],
+      $0: 'cdk',
+      ID: 12345,
+      id: 12345,
+    };
+    expect(findUnknownOptions(argv)).toEqual([]);
+  });
+
+  test('resolves synth alias (synthesize -> synth)', () => {
+    const argv = {
+      _: ['synthesize'],
+      $0: 'cdk',
+      exclusively: true,
+      e: true,
+    };
+    expect(findUnknownOptions(argv)).toEqual([]);
+  });
+
   test('still reports truly unknown options even when CDK_ env vars exist', () => {
     process.env.CDK_INTEG_ATMOSPHERE_POOL = 'test-pool';
     try {