The French striker joined the Black Cats for free over the summer after being released by Tottenham Hotspur.
"There is quality in the side and I am very happy to be part of such an enjoyable way to play football," the 34-year-old told the club's official website.
"It's great to be here. In the manager's mind I think he can see clearly that he wants nice football and to see the players enjoying themselves.
"We have a good team and can look for good things this season. I'm pretty sure that at the end of the day we are going to be happy."
Sunderland resume their Premier League campaign after the international break at home to Liverpool on September 15.