Senior Vice President and General Manager Ruben Amaro Jr. announced Monday that Castillo will report to camp as a non-roster invitee.
Castillo won three Gold Gloves, was a two-time NL stolen base champion and helped the 2003 Florida Marlins win the World Series. He is a career .290 hitter with 370 steals in 15 seasons with the Marlins, Minnesota and the Mets. He stole 62 bases in 84 tries in 2000; he was 8 for 11 last year.
"I think a change will be good for him, I respect him as a player," said Phillies catcher Brian Schneider, who played with Castillo in New York. "He's been in the game a long time and he's done a lot of great things. I think this is a good opportunity for him with what's going on here."
Castillo, 35, hit .235 with no homers and 17 RBIs last season in 247 at-bats.
On Friday, the New York Mets released Luis Castillo despite still owing the three-time All-Star $6 million, in the final season of a four-year, $25 million deal. The Mets are responsible for most of the $6 million remaining on the deal, with the Phillies having to pay Castillo the major-league minimum of $414,000 if he's added to the roster.
The Phillies' second base situation is unsettled because of All-Star Chase Utley's knee woes. Utley has not played in any of the Phillies' exhibition games this spring because of patella tendinitis in his right knee.
Action News sports reporter Jeff Skversky said Utley and the Phils are trying to avoid surgery at all costs. There was a glimmer hope Sunday as both Utley and manager Charlie Manuel indicated that Chase is getting a little better, but it's going to take time.
The Associated Press and ESPN contributed to this article.