The 26-year-old, who has not featured for Sunderland this season, could make his debut for the Championship side against QPR on Saturday.
The former Chelsea trainee is the first player to join Leeds since Steve Evans was appointed head coach last month.
Meanwhile, the Black Cats have recalled winger Will Buckley, 26, from his loan spell with the Elland Road side.
Buckley joined the club on a three-month loan in October, but has not played in any of the club's last four matches.
Leeds United have signed Sunderland midfielder Liam Bridcutt on loan until the start of January.