The Jets kicked off free agency by keeping one of their own.

The team agreed to a deal with linebacker Jamien Sherwood on a new contract Sunday, a source confirmed. The deal is for three years and $45 million, with $30 million guaranteed, a huge amount for a player who did not even begin the season in the starting lineup.

This is the first significant signing by new general manager Darren Mougey as he locks up the player who was voted team MVP last year.

The 25-year-old began last season as a backup, but ended up starting 16 games as C.J. Mosley dealt with injuries.

Sherwood had 158 tackles, showing he could be a full-time starter for the team.

The Jets drafted Sherwood in the fifth round of the 2021 draft. He was a safety at Auburn who was moved to linebacker with the Jets.

Sherwood only made seven starts in his first three seasons, but emerged last year in Mosley’s absence.

The Jets now have a strong pair of starting linebackers under contract with Sherwood and Quincy Williams manning the middle for new coach Aaron Glenn.

Sherwood was viewed as the Jets’ top priority among their own free agents.

They are expected to lose cornerback D.J. Reed and тιԍнт end Tyler Conklin in free agency this week.

The Jets would have created another hole in their defense if they let Sherwood walk. They already need to address defensive line, cornerback and safety in free agency and the draft.

Sherwood was the team’s leading tackler and also had two sacks last season. He was the defensive signal-caller, as well.