The Tigers selected Sweeney's contract from Triple-A Toledo on Friday.
Acquired from the Dodgers in last month's Jack Flaherty trade, Sweeney has slashed .267/.345/.450 with 15 home runs and 20 stolen bases over 107 contests at the Triple-A level this season. The 24-year-old has played shortstop almost exclusively in the minors and should see most of the reps there against right-handers, with Javier Baez perhaps limited to a short-side platoon.