The 26-year-old former Leeds United striker has agreed a one year deal at Ashton Gate and will put pen to paper, subject to the successful completion of a medical, on Sunday and could make his City debut in the pre-season friendly against local rivals Bristol Rovers on Monday.
"Everything is now tied up at the Sunderland end and Michael has agreed a one-year contract, with a further year's option," manager Brian Tinnion told the clubs official website.
"Everything is now tied up at the Sunderland end and Michael has agreed a one-year contract, with a further year's option," manager Brian Tinnion told the clubs official website.
"I don't anticipate any problems with the medical because Michael's injury problems were more than two years ago.
"He played regular reserve team football for Sunderland last season and we wouldn't be signing him if we felt there was any doubt about him playing a full part in our season.
"It's a very exciting signing because Michael has proved himself a Premiership player and is still at a very good age.
"If all goes smoothly on Sunday, he will be in the squad for the Rovers match and I would expect him to play a part."