Correia, 34, spent the first two months this season pitching for Triple-A Sacramento, which is the Giants' top affiliate. He went 0-1 with a 3.58 ERA in six starts. San Francisco released Correia on May 29 after exercising an opt-out clause in his contract.
"Kevin fills a need by adding depth, durability and experience to our pitching staff," Phillies general manager Ruben Amaro Jr. said in a statement. "We hope that he can give us quality innings to take some heat off the bullpen."
Correia is 76-95 with a 4.59 ERA in 353 games (216 starts) for the Giants (2003-08), Padres (2009-10), Pirates (2011-12), Twins (2013-14) and Dodgers (2014).