Jennings was released by the Mets on Friday, Anthony DiComo of MLB.com reports.
The veteran signed with the organization in April and had been toiling at Triple-A Las Vegas, where he hit just .237 with 25 RBI and 43 strikeouts in 55 games. The 30-year-old is less than three years removed from logging nearly 500 at-bats with the Rays, but at this point his career could be over.