The Royals claimed left-hander Tyler Olson off waivers from the Yankees on Tuesday and optioned him to Triple-A Omaha.
Third baseman Mike Moustakas (torn ACL in his right knee) was transferred to the 60-day disabled list to make room for Olson on the 40-man roster.
The 26-year-old Olson was 1-2 with a 5.27 ERA in 11 games (three starts) for Triple-A Scranton/Wilkes-Barre, striking out 21 batters in 27 1/3 innings. He allowed two runs in 2 2/3 innings of relief in his only Major League appearance this season.
Olson, the Mariners' seventh-round pick in the 2013 Draft, has a 5.63 ERA in 12 career Major League appearances with the Yankees and Mariners.