The 28-year-old moved to Prenton Park from Partick in January 2010 and went on to make 44 appearances for Rovers.
McChrystal recently returned from a loan spell at Scunthorpe and boss Ronnie Moore has decided he is surplus to requirements with the npower League One table-toppers.
"Mark wants to play regular first-team football but I can't guarantee him that so this allows him to find another club," Moore told Tranmere's official website.
"I'd like to thank him for his time at Tranmere and wish him the best of luck in the future."
- Sports & Recreation
- Prenton Park