The Dodgers optioned reliever Javy Guerra to Triple-A Albuquerque to make room on the 25-man roster for De La Rosa.
De La Rosa, 23, had surgery last Aug. 9 after tearing a ligament in his right elbow. He pitched 12 scoreless innings at two levels of the low minor leagues during a rehabilitation assignment. De La Rosa was 4-5 with a 3.71 ERA for the Dodgers last season.
Dodgers manager Don Mattingly said the team will use De La Rosa cautiously coming off the major injury and strictly in relief for the rest of this season. The Dodgers continue to view De La Rosa as a starting pitcher beyond this season.
"He's a power arm, a guy who's one of those guys who's swing-and-miss right out of the gate," Mattingly said. "Rubby's pitched out of the bullpen a little for us when he first came up. Rubby's kind of all-out, all the time so I think it will be an easy transition. I think the transition still is being back on the mound, being back in the big leagues."
Guerra had been pitching well, with a 2-3 record and 2.66 ERA, but he was the only Dodgers reliever with minor-league options. He figures to return to the team when rosters expand Sept. 1.