Stewart, 31, was returned from a three-game rehab assignment with Triple-A St. Paul, where he pitched three scoreless, hitless innings with five strikeouts and two walks.
Stewart has not played for the Twins since June 25. He was placed on the 15-day IL with right elbow soreness June 27 before being transferred to the 60-day list.
Stewart is 2-0 with a 0.70 ERA for the Twins this year, striking out 35 and walking 11 in 25 games (25⅔ innings).
The Twins acquired Floro in a trade with the Miami Marlins on July 26. Floro, 32, went 2-1 with a 5.29 ERA in 19 bullpen appearances for Minnesota.
Floro is 5-6 with a 4.76 ERA this year between the Marlins (43 games) and the Twins. He registered seven saves for Miami. He has a 3.42 career ERA with a 26-22 record and 32 saves.