Isringhausen, 39, was 3-3 with a 4.05 ERA and seven saves in 53 games for the New York Mets last season after missing 2010 recovering from ligament-replacement surgery in his right elbow. Isringhausen ranks third among active relievers with 300 saves.
The Angels had a busy offseason, signing slugger Albert Pujols and starting pitcher C.J. Wilson, but general manager Jerry Dipoto made just one move to bolster the bullpen, adding 39-year-old setup man LaTroy Hawkins.
The Angels led the American League with 25 blown saves last season.
Isringhausen is 48-53 with a 3.62 ERA and 1.33 WHIP in a career that stretches back to 1995. He was once a top starting-pitching prospect for the Mets, but after a series of injuries and mishaps was converted to relief. He helped the Oakland A's reach the playoffs in 2000 and 2001 before signing as a free agent with the St. Louis Cardinals, his hometown team, where he was Pujols' teammate for seven seasons.
Mark Saxon covers the Angels for ESPNLosAngeles.com. Follow him on Twitter.