Padilla had surgery on his right arm in February to free up a nerve that was trapped by a muscle. He spent 68 games on the DL last year with elbow soreness and a neck injury.
The Dodgers announced the move before Friday's game at the Chicago Cubs. Padilla takes the roster spot of right-hander Ramon Troncoso, optioned to Triple-A Albuquerque on Thursday.
Padilla, who agreed to a $2 million, one-year deal in December, went 6-5 with a 4.07 ERA in 16 starts for Los Angeles in 2010 but will begin this season in the bullpen.