The Marlins released Smith on July 22.
Smith (finger) was reinstated from the 10-day injured list and outrighted to Triple-A New Orleans on Thursday.
Smith was placed on the 10-day injured list with a fractured nail Thursday.
Smith (1-1) allowed five runs on five hits (one home run) while striking out one through an inning of work Wednesday as he was handed the loss against the Braves.
Smith allowed one walk and struck out two in a scoreless inning to earn the save Wednesday against the Blue Jays.
Smith will start Game 2 of Wednesday's doubleheader against the Orioles, Craig Mish of SportsGrid.com reports.
Smith was promoted to the Marlins' big league roster, Joe Frisaro of MLB.com reports.
Smith is part of the Marlins' 60-man player pool, Craig Mish of SportsGrid.com reports.
Smith signed a minor-league contract which includes an invitation to spring training with the Marlins on Wednesday.
Smith refused an assignment to Triple-A Pawtucket on Monday and elected free agency, Ian Browne of MLB.com reports.