The 35-year-old, who scored 15 goals in 385 appearances in all competitions during two spells at the Proact Stadium, was due to leave at the end of the season.
Allott first joined Chesterfield 11 years ago and chief executive Chris Turner has paid tribute to him, telling the club's official website: "Mark has been a superb professional, winning Player of the Year awards and giving his all for the club over the years.
"I'd like to take this opportunity, on behalf of the club, to thank him for his loyal service and wish him well for the future.
"Paul Cook has decided that Mark does not figure in his first-team plans so a mutually acceptable deal has been agreed which will give him an opportunity to seek a new club."
Commenting on his exit, Allott said: "I'd like to thank the fans and everyone I've worked with during my time at the club. I've made many friends here and experienced every emotion, helping Chesterfield win the League Two title and the Johnstone's Paint Trophy at Wembley, as well as suffering relegation."