Blues boss Alex McLeish has confirmed that Ridgewell will return to the squad for the Third Round tie against former Blues boss Steve Bruce's side at the Stadium of Light on Tuesday night.
However, Ridgewell will be playing in the left-back role and not in his customary centre-back role because Stephen Carr felt a slight reaction on a thigh strain during the 1-0 away win at Hull City at the weekend.
Ridgewell has not played a competetive match since breaking his leg in Blues' 1-1 home draw against Plymouth Argyle on Monday, 13th April.
"He won't play the whole game, but he'll certainly start the game," Blues boss Alex McLeish has said.
"His fitness is perfect."