Reagins, who became general manager in October 2007, will remain with the Angels as a special assistant to club chairman Dennis Kuhl, the Major League Baseball team said.
"Though we finished 2011 with a winning record, we remained short of our objective in winning a championship," Angels owner Arte Moreno told the team's website (http://losangeles.angels.mlb.com).
"In moving forward, we felt a change was needed. Throughout his career, Tony has meant a great deal to this organization, and represented the Angels with the utmost loyalty and dedication. He will always remain part of the Angels family."
The Angels, who won the American League West division in Reagins's first two seasons as general manager, finished second behind the Texas Rangers this year after posting an 86-76 record.
(Writing by Mark Lamport-Stokes in Los Angeles; Editing by Julian Linde)