Hanrahan, the recovering hard-throwing star, signed a one-year major league deal for $1 million guaranteed and a chance to make it $3 million with incentives. The agreement was first reported by CBSSports.com and the terms by USA Today.
The Tigers are a World Series favorite but have struggled out of the pen so far, so Hanrahan will represent a chance at a major improvement.
Hanrahan would appear to be the logical set-up man for Detroit, which signed star closer Joe Nathan this winter. Phil Coke has struggled, and Bruce Rondon went down with an elbow injury in spring training. Detroit has a 5.37 ERA out of the pen so far, second worst in the majors. The Tigers placed Hanrahan on the 15-day disabled list but said they will announce a corresponding move later Friday so he can be placed on the 40-man roster.
Hanrahan threw well for about 20 teams a couple weeks ago and is almost exactly a year removed from Tommy John surgery.
The Yankees, Rangers, Red Sox and Rockies also showed keen interest in Hanrahan and were in the running for his services.
Hanrahan, 32, has 100 career saves and was an All-Star closer for the Pirates from 2011-12.