diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 2d3e6723ad..bacb9d714e 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Delete the deprecated constant `ActiveRecord::ImmutableRelation`.
+
+    *Xavier Noria*
+
 *   Fix duplicate callback execution when child autosaves parent with `has_one` and `belongs_to`.
 
     Before, persisting a new child record with a new associated parent record would run `before_validation`,
diff --git a/activerecord/lib/active_record/errors.rb b/activerecord/lib/active_record/errors.rb
index 0065e65f83..bc039f19aa 100644
--- a/activerecord/lib/active_record/errors.rb
+++ b/activerecord/lib/active_record/errors.rb
@@ -484,11 +484,6 @@ def initialize(model = nil, description = nil)
   #   relation.limit!(5)              # => ActiveRecord::UnmodifiableRelation
   class UnmodifiableRelation < ActiveRecordError
   end
-  deprecate_constant(
-    :ImmutableRelation,
-    "ActiveRecord::UnmodifiableRelation",
-    deprecator: ActiveRecord.deprecator
-  )
 
   # TransactionIsolationError will be raised under the following conditions:
   #
diff --git a/activerecord/test/cases/errors_test.rb b/activerecord/test/cases/errors_test.rb
index 4843529566..4f701a2085 100644
--- a/activerecord/test/cases/errors_test.rb
+++ b/activerecord/test/cases/errors_test.rb
@@ -16,11 +16,4 @@ def test_can_be_instantiated_with_no_args
       end
     end
   end
-
-  def test_active_record_immutable_relation_deprecation
-    expected_message = "ActiveRecord::ImmutableRelation is deprecated! Use ActiveRecord::UnmodifiableRelation instead"
-    assert_deprecated(expected_message, ActiveRecord.deprecator) do
-      assert_same ActiveRecord::UnmodifiableRelation, ActiveRecord::ImmutableRelation
-    end
-  end
 end