The agreement was initially reported by CBSSports.com.
Williams, originally a 2011 fifth-round pick of the Packers out of Arkansas, was claimed off of waivers by Jacksonville in September after being waived by Green Bay at the conclusion of training camp.
Williams, the John Mackey award winner in 2010 as the nation's top tight end in college football, has nine career catches for 70 yards.
The Patriots had just two tight ends active against the Broncos on Sunday night, because Michael Hoomanawanui was forced to sit out because of a knee injury suffered in Week 11. It is unclear whether Hoomanawanui's injury will cause him to miss any further time.
Rob Gronkowski, the team's top tight end, played all 86 of the offensive snaps against Denver, the first time he has done so this season. Veteran Matthew Mulligan played 24 snaps in a reserve role, while the Patriots have also used fullback James Develin in a tight end role at times this season.
Because the Patriots have a full active roster at 53 players, a corresponding transaction will need to be made to clear room for Williams.