Yarbrough (head) will begin a rehab assignment with the Royals' Arizona Complex League affiliate Monday.
Yarbrough has been on the injured list since May 8 after being hit in the head by a line drive, and he was transferred to the 60-day IL in mid-May. However, he faced hitters Wednesday and has now been cleared to return to game action in the minors. The southpaw isn't eligible to be activated until early July, but he should have plenty of time to build back up during his rehab assignment.