The Royals claimed off waivers right-hander Guillermo Moscoso from the Rockies and catcher Brett Hayes from the Marlins during a series of moves Friday.
Kansas City also lost right-hander Blake Wood to a claim by the Cleveland Indians.
Moscoso was 3-2 with a 6.12 ERA for Colorado, but was 8-10 with a 3.38 ERA while starting 21 of 23 games two years ago in Oakland. Hayes hit .202 in 39 games for Miami last season.
In other news, left-hander Danny Duffy and right-hander Felipe Paulino, a pair of starters who underwent Tommy John surgery this season, were reinstated from the 60-day disabled list.
Catcher Manny Pina was assigned outright to Triple-A Omaha, while left-hander Tommy Hottovy, right-hander Jeremy Jeffress and outfielder Jason Bourgeois were designated for assignment.