Westbrook, who had been on the DL since April 22 with a strained left muscle in the rib area, was 1-2 with a 2.73 ERA in four starts before the injury. He was injured April 19 against Minnesota. It was the fifth career trip to the DL for Westbrook, who is 63-64 in six major league seasons.
Westbrook, 30, made two minor league rehab starts before being activated. His return comes five days after right-hander Fausto Carmona went on the DL with a strained hip. Carmona is expected to miss four weeks. The Indians will go with a rotation of Westbrook, left-handers C.C. Sabathia, Cliff Lee and Aaron Laffey and right-hander Paul Byrd.
Right-hander Jorge Julio, who made the team as a non-roster invitee in spring training, was designated for assignment. He had no record and a 5.60 ERA in 15 relief appearances.