Douglas received a six-year contract, a source told ESPN's Adam Schefter.
Douglas spent the last three years in Philadelphia, serving as the Eagles' vice president of player personnel. He helped construct the roster that delivered Philly its first-ever championship two seasons ago.
Douglas was widely considered the favorite to become the new general manager in New York after Mike Maccagnan was fired on May 15. He and first-year Jets head coach Adam Gase worked together in 2015 with the Chicago Bears.
The Jets considered four finalists for the job: Douglas, Seattle Seahawks co-director of player personnel Scott Fitterer, Chicago Bears assistant director of player personnel Champ Kelly, and New Orleans Saints director of pro scouting Terry Fontenot.
Gang Green last made the playoffs in 2010, though the organization is well-positioned for the future given its salary-cap situation and the presence of young quarterback Sam Darnold. The same agent, Jimmy Sexton, represents Douglas, Darnold, and Gase, according to Yahoo Sports' Charles Robinson.