The move was made Friday before Baltimore opened a series against the Los Angeles Angels. Johnson had been sidelined since May 28 because of inflammation in his right elbow.
Johnson was 1-1 with one save and a 6.22 ERA in 10 appearances before the injury. He fills the roster spot vacated when right-hander Armando Gabino was optioned to Triple-A Norfolk after Thursday night's loss to the Chicago White Sox.
This is Johnson's fifth season with the Orioles. The right-hander was 4-6 with a 4.11 ERA and 10 saves in 64 relief appearances last season. He spent his first two big league seasons as a starter and was converted into a reliever in 2008, when he pitched 68 2-3 innings in 54 outings without allowing a home run.