diff --git a/doc/main/micropython/builtins.rst b/doc/main/micropython/builtins.rst
index 56a80c5..13267d7 100644
--- a/doc/main/micropython/builtins.rst
+++ b/doc/main/micropython/builtins.rst
@@ -7,6 +7,8 @@ Classes and types
 
 .. autoclass:: ubuiltins.bool
 
+.. autoclass:: ubuiltins.bytearray
+
 .. autoclass:: ubuiltins.bytes
 
 .. autoclass:: ubuiltins.complex
diff --git a/src/ubuiltins/__init__.py b/src/ubuiltins/__init__.py
index 8738686..232ec39 100644
--- a/src/ubuiltins/__init__.py
+++ b/src/ubuiltins/__init__.py
@@ -42,6 +42,7 @@ import usys
 # These get overridden later on, but we still want to use the originals
 # for the purpose of typing the doc strings.
 _bool = bool
+_bytearray = bytearray
 _bytes = bytes
 _callable = callable
 _complex = complex
@@ -143,6 +144,33 @@ class bytes:
         """
 
 
+class bytearray:
+    @overload
+    def __init__(self) -> None:
+        ...
+
+    @overload
+    def __init__(self, source: _int) -> None:
+        ...
+
+    @overload
+    def __init__(self, source: Union[_bytes, _bytearray, _str, Iterable[_int]]) -> None:
+        ...
+
+    def __init__(self, *args):
+        """
+        Creates a new ``bytearray`` object, which is a sequence of integers
+        in the range ``0 <= x <= 255``. This object is mutable, which means
+        that you can change its contents after you create it.
+
+           * If no argument is given, this creates an empty ``bytearray``.
+           * If the ``source`` argument is an integer, this creates a ``bytearray``
+             of zeros. The argument specifies how many zeros.
+           * For all other valid ``source`` arguments, this creates a bytearray with
+             the same byte sequence as the given ``source`` argument.
+        """
+
+
 def callable(object: Any) -> _bool:
     """
     Returns ``True`` if the object argument appears callable, ``False`` if not.