Phillips, 26, signed a one-year contract with the Eagles in March. The team was hoping he could recover from the knee injuries that plagued him while he was in New York and join Patrick Chung in a revamped defensive secondary.
But Phillips was bothered by a quadriceps injury during training camp. He was expected to play Saturday night in Jacksonville.
"Nobody wants to be on the field more than Kenny right now," defensive coordinator Bill Davis said last week. "He's an experienced vet, which helps, but not experienced in this system."
Phillips dressed for the game, but was unable to go after warming up. His release now gives him time before the regular season to find a new team.
Could it be his old team? The Giants lost safety Stevie Brown to a torn ACL. Phillips would be familiar, but it was his injury issues that made him expendable after last season.
The Eagles will go with Chung and Nate Allen at safety, unless general manager Howie Roseman can find help via trade or the waiver wire.