Mosley, who suffered a severe groin injury in Week 1, was placed on injured reserve Tuesday. He will have surgery to repair what he described as a groin/abdominal issue.
"It gives us a chance to get him back in the spring and get him going in the offseason program," coach Adam Gase said on The Michael Kay Show on ESPN New York radio.
Mosley told ESPN 10 days ago that his hope was that a recent platelet-rich plasma injection would heal the injury, with surgery a last resort. His goal was to test the groin this week by resuming football activities, but the plan was aborted.
Mosley became the 15th Jets player on injured reserve.
After sitting out four games following the initial injury, Mosley returned Oct. 21 against the New England Patriots and aggravated it. At the time, the Jets called it a six-week injury, so they gave him a chance to rehab instead putting him on IR.
This will go down as one of the most disappointing moves in recent free-agent history. The Jets lured Mosley away from the Baltimore Ravens with a five-year, $85 million contract -- then a record-setting deal for an inside linebacker. It included a franchise-record $43 million in guarantees.
They anointed him as the "quarterback" of their defense and expected him to galvanize the unit. Without Mosley, the defense has played well; the Jets are ranked sixth in yards allowed.
Mosley got off to a terrific start, scoring the Jets' first touchdown of the season on an interception return in the opener. He was dominant in that game, an eventual 17-16 loss to the Buffalo Bills, but injured his groin in the third quarter.
His stat line for the season: two games played, 108 defensive snaps, nine tackles, one interception and one fumble recovery. His 2019 compensation is $19 million.
Mosley isn't going anywhere because his 2020 salary ($6 million) is fully guaranteed. So is $8 million of his $16 million salary in 2021.
The Jets claimed safety Bennett Jackson off waivers from the Ravens in a corresponding move Tuesday.
The Jets went into the preseason thinking they had one of the better inside-linebacker tandems in the league, but Avery Williamson also suffered a season-ending knee injury in a preseason game.