The ex-England international, who has previous Premier League experience with West Bromwich Albion, Everton and Manchester City, has been without a club since leaving Greek side AEK Athens two months ago.
He becomes David Moyes' first signing of the January transfer window and could make his debut against Crystal Palace in the Premier League next week when the Black Cats face their former manager Sam Allardyce for the first time since he left Wearside to take the England job.
The 34-year-old will link up with former boss Moyes at the Stadium of Light, for whom he worked under for three successful years at Everton. And the former Wolves man told safc.com he believes the Scotsman is the man to keep Sunderland afloat. "He's a well-experienced manager. Obviously the situation we are in isn't great but if anyone can get us out it is him".
Lescott is also looking forward to linking up with former team-mates Victor Anichebe and Jermain Defoe. "Victor I've obviously played with a few times and me and Jermain go back to the under 16s, so there are a few familiar faces there which helps when you're moving to a new team," the Birmingham-born centre-back added.
Sunderland currently sit bottom of the Premier League table, without a win in their last seven matches in all competitions, and three points adrift from safety.
Lescott will be hoping his fortunes are about to change after he tasted relegation with boyhood club Aston Villa last season, featuring 33 times in a side which was dubbed as the 'worst ever'.
He won two Premier League titles during a successful five-year spell at City and has also played for West Bromwich Albion, Everton, where he played under Moyes, and Wolves.