Fister agreed to be optioned to Class A Inland Empire but likely will be promoted soon to the 40-man roster, as Los Angeles is dealing with injuries to starters Garrett Richards (biceps strain) and Tyler Skaggs (oblique).
Fister posted a 12-13 mark with a 4.64 ERA last season with the Houston Astros. The 33-year-old is three years removed his best season, in which he produced a 16-6 record with a 2.41 ERA for the Washington Nationals.
In a corresponding move, the Angels shuffled right-hander Andrew Bailey (shoulder) from the 10-day disabled list to the 60-day DL. He has been out since April 10 due to right shoulder inflammation.
Bailey, 32, has struck out two without allowing a hit over three scoreless innings early this season before landing on the DL.