Bolanos was recalled from Triple-A Omaha on Thursday, Anne Rogers of MLB.com reports.
Bolanos failed to land a spot on the Royals' Opening Day roster this year, but he'll now join the major-league club after Kyle Isbel was sent down. The right-hander has made three minor-league starts this season and has posted a 3.38 ERA and 1.20 WHIP in 13.1 innings.