His contract included a $3 million club option for the 2019 season. Peralta was designated for assignment on March 28, 2018. He cleared waivers and was outrighted to the Class AAA Omaha Storm Chasers. He was recalled by the Royals on June 17. During the month of June, he made five appearances in relief, allowing one run in innings pitched and recording two saves. On the season, Peralta pitched exclusively out of the bullpen, recording 14 saves in 37 appearances. Through July 19, 2019, Peralta appeared in 42 games, posting an ERA of 5.80 with 2 saves. On July 20, 2019, Peralta was designated for assignment. On July 24, 2019, Peralta was released from the Royals after clearing waivers.