diff --git a/.changes/next-release/enhancement-s3-41977.json b/.changes/next-release/enhancement-s3-41977.json
new file mode 100644
index 000000000000..646099011468
--- /dev/null
+++ b/.changes/next-release/enhancement-s3-41977.json
@@ -0,0 +1,5 @@
+{
+  "type": "enhancement",
+  "category": "``S3``",
+  "description": "Add support for creating S3 account regional namespace buckets with ``aws s3 mb``. The command now automatically detects bucket names matching the account-regional naming pattern and sets the required ``x-amz-bucket-namespace`` header."
+}
diff --git a/awscli/customizations/s3/subcommands.py b/awscli/customizations/s3/subcommands.py
index 1a4a90855c2c..388aca66d1f7 100644
--- a/awscli/customizations/s3/subcommands.py
+++ b/awscli/customizations/s3/subcommands.py
@@ -31,7 +31,7 @@
 from awscli.customizations.s3.utils import find_bucket_key, AppendFilter, \
     find_dest_path_comp_key, human_readable_size, \
     RequestParamsMapper, split_s3_bucket_key, block_unsupported_resources, \
-    S3PathResolver
+    S3PathResolver, is_account_regional_namespace_bucket
 from awscli.customizations.utils import uni_print
 from awscli.customizations.s3.syncstrategy.base import MissingFileSync, \
     SizeAndLastModifiedSync, NeverSync, AlwaysSync
@@ -910,6 +910,9 @@ def _run_main(self, parsed_args, parsed_globals):
         bucket_config = {}
         bucket_tags = self._create_bucket_tags(parsed_args)
 
+        if is_account_regional_namespace_bucket(bucket):
+            params['BucketNamespace'] = 'account-regional'
+
         # Only set LocationConstraint when the region name is not us-east-1.
         # Sending LocationConstraint with value us-east-1 results in an error.
         if self.client.meta.region_name != 'us-east-1':
diff --git a/awscli/customizations/s3/utils.py b/awscli/customizations/s3/utils.py
index a2809755e2b1..9051ef69bc09 100644
--- a/awscli/customizations/s3/utils.py
+++ b/awscli/customizations/s3/utils.py
@@ -64,6 +64,10 @@
 )
 
 
+def is_account_regional_namespace_bucket(bucket):
+    return bucket.endswith('-an')
+
+
 def human_readable_size(value):
     """Convert a size in bytes into a human readable format.
 
diff --git a/tests/functional/s3/test_mb_command.py b/tests/functional/s3/test_mb_command.py
index 7ea29c8d2b22..5f5675528b97 100644
--- a/tests/functional/s3/test_mb_command.py
+++ b/tests/functional/s3/test_mb_command.py
@@ -90,6 +90,40 @@ def test_make_bucket_with_multiple_tags(self):
         }
         self.assert_params_for_cmd(command, expected_params)
 
+    def test_account_regional_namespace_bucket(self):
+        bucket = 'amzn-s3-demo-bucket-111122223333-us-west-2-an'
+        command = self.prefix + f's3://{bucket} --region us-west-2'
+        self.parsed_responses = [{'Location': 'us-west-2'}]
+        expected_params = {
+            'Bucket': bucket,
+            'BucketNamespace': 'account-regional',
+            'CreateBucketConfiguration': {'LocationConstraint': 'us-west-2'},
+        }
+        self.assert_params_for_cmd(command, expected_params)
+
+    def test_account_regional_namespace_bucket_us_east_1(self):
+        bucket = 'my-bucket-111122223333-us-east-1-an'
+        command = self.prefix + f's3://{bucket} --region us-east-1'
+        expected_params = {
+            'Bucket': bucket,
+            'BucketNamespace': 'account-regional',
+        }
+        self.assert_params_for_cmd(command, expected_params)
+
+    def test_account_regional_namespace_short_bucket_name(self):
+        bucket = 'xyz-an'
+        command = self.prefix + f's3://{bucket} --region us-east-1'
+        expected_params = {
+            'Bucket': bucket,
+            'BucketNamespace': 'account-regional',
+        }
+        self.assert_params_for_cmd(command, expected_params)
+
+    def test_regular_bucket_no_namespace(self):
+        command = self.prefix + 's3://my-regular-bucket --region us-east-1'
+        expected_params = {'Bucket': 'my-regular-bucket'}
+        self.assert_params_for_cmd(command, expected_params)
+
     def test_tags_with_three_arguments_fails(self):
         command = self.prefix + 's3://bucket --tags Key1 Value1 ExtraArg'
         self.assert_params_for_cmd(
diff --git a/tests/integration/customizations/s3/test_plugin.py b/tests/integration/customizations/s3/test_plugin.py
index 4aab3dd74a04..95a71bc3a33d 100644
--- a/tests/integration/customizations/s3/test_plugin.py
+++ b/tests/integration/customizations/s3/test_plugin.py
@@ -190,6 +190,13 @@ def setUp(self):
         super(BaseS3IntegrationTest, self).setUp()
 
 
+class TestMakeBucketAccountRegionalNamespace(BaseS3IntegrationTest):
+    def test_short_an_suffix_sends_namespace_header(self):
+        p = aws('s3 mb s3://xyz-an')
+        assert p.rc != 0
+        assert 'InvalidBucketNamespace' in p.stderr
+
+
 class TestMoveCommand(BaseS3IntegrationTest):
     def assert_mv_local_to_s3(self, bucket_name):
         full_path = self.files.create_file('foo.txt', 'this is foo.txt')
diff --git a/tests/unit/customizations/s3/test_utils.py b/tests/unit/customizations/s3/test_utils.py
index 96d4e216c44c..7a29b8f01b9d 100644
--- a/tests/unit/customizations/s3/test_utils.py
+++ b/tests/unit/customizations/s3/test_utils.py
@@ -40,7 +40,8 @@
     ProvideLastModifiedTimeSubscriber, DirectoryCreatorSubscriber,
     DeleteSourceObjectSubscriber, DeleteSourceFileSubscriber,
     DeleteCopySourceObjectSubscriber, NonSeekableStream, CreateDirectoryError,
-    S3PathResolver, CaseConflictCleanupSubscriber)
+    S3PathResolver, CaseConflictCleanupSubscriber,
+    is_account_regional_namespace_bucket)
 from awscli.customizations.s3.results import WarningResult
 from tests.unit.customizations.s3 import FakeTransferFuture
 from tests.unit.customizations.s3 import FakeTransferFutureMeta
@@ -360,6 +361,44 @@ def test_outpost_bucket_arn_with_slash_raises_exception(self):
             )
 
 
+class TestIsAccountRegionalNamespaceBucket(unittest.TestCase):
+    def test_matches_standard_pattern(self):
+        self.assertTrue(
+            is_account_regional_namespace_bucket(
+                'amzn-s3-demo-bucket-111122223333-us-west-2-an'
+            )
+        )
+
+    def test_matches_different_region(self):
+        self.assertTrue(
+            is_account_regional_namespace_bucket(
+                'my-bucket-123456789012-eu-central-1-an'
+            )
+        )
+
+    def test_no_match_regular_bucket(self):
+        self.assertFalse(
+            is_account_regional_namespace_bucket('my-regular-bucket')
+        )
+
+    def test_no_match_missing_an_suffix(self):
+        self.assertFalse(
+            is_account_regional_namespace_bucket(
+                'bucket-111122223333-us-west-2'
+            )
+        )
+
+    def test_matches_short_bucket_name(self):
+        self.assertTrue(
+            is_account_regional_namespace_bucket('xyz-an')
+        )
+
+    def test_no_match_express_directory_bucket(self):
+        self.assertFalse(
+            is_account_regional_namespace_bucket('bucket--usw2-az1--x-s3')
+        )
+
+
 class TestCreateWarning(unittest.TestCase):
     def test_create_warning(self):
         path = '/foo/'