The move is retroactive to May 7.
Infante missed the club's last five games because of his back issues. The veteran is batting .267 with two homers and 19 RBI over 30 games this season.
The Royals selected the contract of infielder Pedro Ciriaco from Triple-A Omaha in a corresponding move.
Ciriaco appeared in one game this year for the Royals before being designated for assignment on April 5. He was hitting .305 with a home run and six doubles in 19 games for Omaha.