The 35-year-old put pen to paper on Friday after passing a medical, and although he will not be involved in Saturday's Premier League clash at the Stadium of Light, he is eager to take up his new challenge.
He told the club's official website: "I'm very excited to be here.
"It is another challenge and hopefully I can use my experience to help the young players at the club. I had a few options and I just thought this is a good one.
"I want to get a good week or 10 days' training under my belt and go from there."