Dodgers manager Joe Torre said Billingsley "felt a little something up in the high groin area" in the final inning of his last start against the Angels.
Billingsley underwent an MRI, and Torre said everything looked fine. However, he was tight when he tried to throw on Tuesday, and Torre said the DL was the safest option.
"It's [a groin injury], the one you can predict the least, because you can warm up, you can have a simulated game, but until you get on the mound and push off in a regular game, you're never sure," Torre said. "So we're going to take the safe route."
In 13 starts this season, Billingsley is 6-4 with a 4.34 ERA. He was scheduled to pitch in Thursday's series finale at Cincinnati.
Because of Monday's off-day, the Dodgers can keep the rotation on normal rest. John Ely will move up to take Billingsley's spot Thursday, and Carlos Monasterios will pitch Friday at Boston. Vicente Padilla will return from the DL after recovering from an irritated nerve in his forearm and start Saturday.
Torre said Billingsley took part in the discussion about whether a move would be made, and Billingsley told him it would be his decision.
"He wanted to pitch," Torre said. "But I think everything we said to him pretty much made sense."
Torre said the Dodgers would add a relief pitcher Wednesday to take Billingsley's spot on the roster.
Matt Brown is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.