Burres, who made 20 appearances for Pittsburgh in 2010, was non-tendered by the Pirates on Dec. 2. That removed the left-hander from the 40-man roster, though general manager Neal Huntington said at the time that the club was interested in bringing Burres back.
Burres went 4-5 with a 4.99 ERA in 20 games (13 starts) last season.
He joined the rotation early in the year and, after spending much of the summer back in Triple-A, the left-hander stepped back in as a starter for the final month of the season.
The Pirates will probably build Burres up as a starter during Spring Training, though it seems likely that he'll start the year in Triple-A Indianapolis' rotation. His presence will give the Pirates additional starting pitching depth.
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.