The Blue Jays made the move Thursday and also recalled right-hander Brad Lincoln from Triple-A Buffalo.
Johnson was scratched from a start Friday, and his move to the DL was retroactive to April 29. He is 0-1 with a 6.86 ERA in four starts since being acquired in an offseason trade with Miami.
Romero will start Friday night at home against Seattle. He was an All-Star in 2011, but struggled in spring training this year and began the season in the minors to work on his mechanics.
Romero made one start for Class A Dunedin, allowing one run in seven innings.
More Sports Headlines
Seahawks escape with 13-10 victory over winless Lions Lions force Seahawks' Wilson to run for his life Seahawks' defense benefits from missed call Seahawks cornerback Williams plays his best game against Lions Seahawks report card Seahawks improve to 22-8 on MNF Huskies' Petersen thinks Trojans are underrated? Rams linebacker Ogletree to have surgery for broken right ankle
Our new comment system is not supported in IE 7. Please upgrade your browser here.