Bedard, 33, made 24 starts for the Pirates last year and went 7-14 with a 5.01 ERA, allowing 129 hits in 125 2/3 innings. In his nine-year Major League career, he's 63-64 with a 3.85 ERA with the Orioles, Mariners, Pirates and Red Sox.
Astros general manager Jeff Luhnow said Bedard is likely to take a spot in the Houston rotation this year behind right-handers Bud Norris, Lucas Harrell and Jordan Lyles. He started on Opening Day for the Pirates last year.
"When you have a lot of right-handers in the mix and to have a left-hander with his type of Major League experience and success and track record, it can only help us," Luhnow said. "He's got a strong chance to be in our rotation all year long, and we're hoping that's the Erik Bedard that's had tremendous success already in his big league career."
Bedard was one of the most effective left-handed starters in the American League from 2006-09, ranking third in winning percentage with a 39-23 (.629) record and second in ERA (3.40) among lefties in that span before being slowed by injuries. He was 13-5 for Baltimore in 2007.
"It doesn't take a lot of imagination to see him as a very, very effective Major League starter," Luhnow said. "He's been very, very effective throughout most of his career, and has had challenges with injuries, but he's still young and has a lot of ambition left in the game."
Among those also battling for rotation spots this spring are right-handers Philip Humber, Alex White, John Ely and Jarred Cosart and left-hander Dallas Keuchel. Lefties Brett Oberholtzer and Rudy Owens will also be in camp, but they're likely to start in the Minor Leagues.
"We're going to take the best five starters, regardless of handedness," Luhnow said.