Mike LaFleur, who most recently served as Kyle Shanahan's passing-game coordinator with the 49ers, will join Robert Saleh's staff with the New York Jets.
LaFleur will become Saleh's top offensive assistant, a source told NBC Sports Bay Area on Thursday night.
The Jets hired Saleh to replace Adam Gase as head coach. Saleh served the past four seasons as 49ers defensive coordinator under Shanahan.
LaFleur, 33, the younger brother of Green Bay Packers head coach Matt LaFleur, previously served as the 49ers' wide receivers/passing game coordinator in 2018 and wide receivers/passing game specialist in 2017.
He previous NFL coaching experience consisted of working in low-level offensive positions under Shanahan as offensive coordinator: two seasons with the Atlanta Falcons and one year with the Cleveland Browns.