Keller elected free agency Tuesday, Alex Speier of The Boston Globe reports.
Keller's tenure in the big leagues afforded him the ability to decline an option to Triple-A Worcester and elect free agency, and the veteran right-hander has exercised that right and will move on from the Red Sox. He holds a 5.30 ERA and 30:13 K:BB over 37.1 innings at the big-league level in 2024.