Here's what Blues said about appointing the 70-year-old as their new boss: "The club is delighted to announce that Harry Redknapp is Blues new manager.
"The vastly experienced Redknapp has agreed to replace Gianfranco Zola, who resigned on Monday.
"Redknapp has enjoyed notable success as a manager at AFC Bournemouth, West Ham United, Portsmouth, Tottenham Hotspur and QPR.
"Amongst his many achievements, he successfully guided Portsmouth and QPR to promotions to the Premier League and also secured an FA Cup victory with Portsmouth.
"He won a Premier League Manager of the Year award with Tottenham Hotspur and also qualified them for the Champions League.
"We believe that under the leadership of Redknapp, Blues will enhance their strength and create achievement."