The 12pm deadline yesterday passed without Bridges finalising terms on a permanent switch to the club where he started his professional career.
But the three-month loan terms agreed with the Bolton striker means he can still play at Elland Road.
Bridges said: "I'm excited to be back. it's amazing how things work out in football. The fact that I started my career here and had such a good rapport with the fans were two of the reasons for me coming back. Mick has a good squad of players and it's my aim to get back into the Premiership."
Bolton boss Sam Allardyce said: "Sunderland are taking over Michael's contract. He needs to be playing first-team football and that would only have happened on a spasmodic basis here.
"Sunderland will be good for him because he is going back to the club where it all started. It's a lower division, but that probably suits him at this moment.
However, Sunderland will not be able to field young forward Simon Johnson, who is on loan from Leeds.