The Blue Jays also recalled Nate Pearson from Triple-A and placed fellow right-hander Hagen Danner on the 15-day injured list with a left oblique strain.
Romano, 30, has been out since late July with lower back inflammation. He was 4-5 with a 2.79 ERA and had 28 saves in his second-consecutive All-Star campaign. The right-hander has a career 18-13 record with a 2.62 ERA and 89 saves in five seasons with the Blue Jays.
The Blue Jays are planning on a short rehab stint, and Romano reportedly is expected back with the major league club by Tuesday.
Pearson, 26, has gone 5-2 with a 5.31 ERA in 32 appearances with Toronto this season.
Danner, 24, made his major league debut Friday against the Chicago Cubs and retired the only batter he faced.
Also on Saturday, Toronto signed free agent right-hander Matt Wisler to a minor league contract.
Wisler, 30, last appeared in the major leagues last season with the Tampa Bay Rays. He was 5-2 with a 4.40 ERA In 39 appearances (two starts) this season for the Detroit Tigers' Triple-A affiliate Toledo.
Over parts of eight major league seasons with seven different clubs, Wisler is 25-36 with a 4.59 ERA in 234 appearances (66 starts).