The right-hander's deal did not come with an invitation to big league camp.
Galarraga, 31, spent most of the 2012 season in the Minor Leagues with the Astros' organization. In five big league starts and 24 innings last season for Houston, he was 0-4 with a 6.75 ERA.
On June 2, 2010, while pitching for the Tigers, Galarraga became famous for being denied a perfect game on the final play vs. the Indians because of a blown call by first-base umpire Jim Joyce.
A six-year Major League veteran of the Rangers, Tigers, D-Backs and Astros, Galarraga is 26-34 with a 4.78 ERA in 100 games, including 91 starts.
Also on Tuesday, Baseball America reported that the Reds signed 18-year-old Dominican left-handed pitcher Jacob Constante for a $730,000 bonus. It was believed to be the largest signing bonus the Reds have agreed to with an international player since the 2012-13 signing period began on July 2.
According to the report, Constante is 6-foot-3 and 215 pounds and can throw his fastball 92-94 mph with an above-average slider but below-average changeup. He will turn 19 in March.