On December 30, 2011, the Red Sox again re-signed Hill to a minor-league contract that included an invitation to spring training. His recovery progressed ahead of schedule and he made his first rehab appearance in the minors, with the Greenville Drive, on April 7, 2012. He made 16 minor league rehab appearances, across five different levels, and had a 2.20 ERA with 27 strikeouts and five walks. He rejoined the Red Sox roster on April 27. He experienced renewed soreness in his elbow on June 10 and was placed back on the disabled list. He was diagnosed with a strained flexor muscle and he didn't rejoin the roster until September 1. Overall, he appeared in 25 games for the Red Sox in 2012, with a 1.83 ERA in innings and 21 strikeouts. He was non-tendered on November 30 and became a free agent.