Jim Vince, the Shaymen's manager, praised Walker as a good role model for his younger players.
"His attitude and professionalism has been first class and I thank him for his support, everyone at the club wishes him well in the future," he said.
"Justin came to the club with a very good reputation and I was grateful he jouned us, however he has found it difficult to sustain a position in the team on a regular basis."
FC Halifax Town play in Division One North of the Unibond League, after being ceated in the summer following the demise of Halifax Town AFC in May 2008.