In his debut for the Braves, Detwiler retired the only hitter he faced -- Anthony Rizzo -- on a grounder to short in the fifth inning of Atlanta's 4-2 win over the Cubs.
The move comes shortly after Atlanta agreed to a deal with veteran righty Jason Frasor, as Jim Johnson could soon be on his way out of town as the July 31 non-waiver Trade Deadline approaches.
The Braves also recalled outfielder Joey Terdoslavich from Triple-A Gwinnett, designated David Carpenter for assignment and sent Jake Brigham down Triple-A.
The Braves entered Friday with the second-worst bullpen ERA in baseball (behind only the Colorado Rockies) at 4.40.
Carlos Collazo is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.