Terms of the deal are not yet known.
Jenkins, 30, had played each of the last two seasons with the Minnesota Vikings after starting his career with the Atlanta Falcons. He hauled in 40 catches for 449 yards and two touchdowns last season.
Originally a first-round pick in 2004 out of Ohio State, Jenkins has the frame to play as an "X" receiver in the Patriots' offense.
Jenkins was used as both a split end ("X") and slot receiver in Minnesota, which focused more on the short-to-intermediate passing game with quarterback Christian Ponder rather than challenging a defense vertically.
Jenkins has a long, wiry build (6-foot-4, 214 pounds) and doesn't rely on speed to get open. He's at his best finding space against zone coverages, and he tries to win in man-to-man coverage with his post-up skills and leverage from his size.
A league source had confirmed the signing to ESPNBoston.com on Thursday afternoon. The story was reported earlier by CBSSports.com.