Rauch appeared in 51 games this season and posted a 5-4 record with 11 saves and a 4.47 earned run average.
The Blue Jays also designated pitcher Trever Miller for assignment and selected the contracts of pitchers Wil Ledezma and Rommie Lewis from Triple-A Las Vegas.
Miller appeared in six games for the Blue Jays, who acquired the 38-year-old in a trade with the Cardinals on July 27, and posted a 4.91 ERA.
Ledezma joins Toronto for the second time this season. He made two appearances, yielding three runs over three innings for the club.
Lewis pitched in 42 games with Las Vegas in 2011, going 3-3 with a 6.60 ERA and four saves.