The 26-year-old midfielder will stay with United until early January, while Sunderland have recalled winger Will Buckley from his loan spell at Elland Road.
Bridcutt will go straight into the squad for Saturday's league game at QPR and becomes head coach Steve Evans' first signing at the club.
"I've been speaking to the manager and he's given me a great opportunity to come and play for a brilliant club," Bridcutt told Leeds United's official website.
"It's been on and off for the last few weeks now. I've had a few other options, but from speaking to the manager he's given me the confidence to come here and show what I can do.
"When the manager shows so much interest in you and puts so much faith in you, you always want to repay that with your performances."
Bridcutt has made 30 Barclays Premier League appearances for Sunderland but has fallen out of favour at the Stadium of Light.
He became prominent with Brighton under Gus Poyet and followed the Uruguayan to Sunderland for a reported £3m fee in January 2014.
Buckley was signed by former Leeds head coach Uwe Rosler in early October but made just one start and three substitute appearances for the club.