diff --git a/airflow/models/baseoperator.py b/airflow/models/baseoperator.py
index 0c3d119be1983..514553e05a2dd 100644
--- a/airflow/models/baseoperator.py
+++ b/airflow/models/baseoperator.py
@@ -45,7 +45,6 @@
     NoReturn,
     Sequence,
     TypeVar,
-    Union,
     cast,
 )
 
@@ -1789,10 +1788,6 @@ def expand_start_trigger_args(self, *, context: Context, session: Session) -> St
         return self.start_trigger_args
 
 
-# TODO: Deprecate for Airflow 3.0
-Chainable = Union[DependencyMixin, Sequence[DependencyMixin]]
-
-
 def chain(*tasks: DependencyMixin | Sequence[DependencyMixin]) -> None:
     r"""
     Given a number of tasks, builds a dependency chain.
diff --git a/docs/spelling_wordlist.txt b/docs/spelling_wordlist.txt
index 4413be1fc746a..78025bfe9fe22 100644
--- a/docs/spelling_wordlist.txt
+++ b/docs/spelling_wordlist.txt
@@ -227,7 +227,6 @@ cgi
 Cgroups
 cgroups
 cgroupspy
-Chainable
 chakra
 Changelog
 changelog
diff --git a/newsfragments/42776.significant.rst b/newsfragments/42776.significant.rst
new file mode 100644
index 0000000000000..5fad7dfe79b66
--- /dev/null
+++ b/newsfragments/42776.significant.rst
@@ -0,0 +1 @@
+Removed deprecated ``Chainable`` type from ``BaseOperator``.