Kimbrel, who saved 46 games last season, became the least-senior member of the relief corps when Cory Gearrin was optioned back to Triple-A Gwinnett to make room for Tim Hudson to come off the disabled list for Sunday's start.
Gearrin didn't get into a game after being called up from the G-Braves on Tuesday, when Jair Jurrjens was sent down to Gwinnett to get back on track.
Gearrin seemed a lock to make the team through most of Spring Training before losing his control during his final few appearances. But he pitched 12 1/3 scoreless innings for Gwinnett with 15 strikeouts to two walks before being promoted.
"Gearrin has been pitching lights-out in Triple-A," Braves manager Fredi Gonzalez said. "So go back down keeping pitching that way and if we need him again, it'll be an easy decision."