Jess joined Northampton from Nottingham Forest two years ago and made 76 appearances during his time at Sixfields.
But he had not figured under Stuart Gray for the past two months and claimed last week that he would be leaving the club.
Gray has now confirmed that the 36-year-old has moved on, with the midfielder expected to quit playing in favour of finding a coaching position.
"Eoin and I sat down and had a chat, and at 36 I don't think he is too keen on carrying on his playing career," Gray told the club's official website.
"He was out of contract in the summer and it made sense to make this decision now.
"I think he wants to move into the coaching side of things and we wish him all the best with that.
"I would also like to thank him for all his efforts at the club and wish him every success for the future."
Sky Sports