The NFL had one more big trade left in it before the close of the deadline.
ESPN first reported the news.
Buffalo later confirmed the trade. The team released running back Joe Banyard to make room on the roster for Benjamin.
It's a chips-in-the-middle for the 5-2 Bills, who are in prime position to bust through their 17-season streak of missing the playoffs.
The Bills brass knows Benjamin well. Buffalo general manager Brandon Beane was in Charlotte when the Panthers made the receiver the No. 28 overall pick in 2014. Bills head coach Sean McDermott was defensive coordinator in Carolina from 2011-2016.
"Size and experience. When he's covered, he's still open," Beane told reporters at a press conference on Tuesday. "He's tough. He's big. He's got great hands. He knows how to run routes. He can block. He's going to be way bigger than the corners he faces, so he can help in the running game there."
Benjamin provides quarterback Tyrod Taylor with a needed big target and red-zone threat. In three seasons played (Benjamin missed 2015 with a knee injury), the 6-foot-5 target has compiled 2,424 yards on 168 receptions and 18 touchdowns. Through eight games this season, Benjamin earned 32 catches for 475 yards and two scores.
Taylor has been winning games this season tossing to a band of second-fiddle receivers. Running back LeSean McCoy leads the Bills in receptions with 38, and tight end Charles Clay, who has missed the past two games, leads in yards with 258. Before the trade, Taylor's top wide receivers were Jordan Matthews (15 catches, 193 yards), Andre Homes (11 for 97) and rookie Zay Jones (10 for 115). Bills wide receivers have caught just five combined touchdowns this season.
Adding Benjamin will give Taylor a big-bodied receiver who can win on the outside and should help open more holes for the running game, especially in the red zone. The wideout, however, comes with injury risk and was dealing with a sore knee earlier this month.
Devin Funchess moves to the top role, with rookie Curtis Samuel and Russell Shepard in the receiver corps. Ed Dickson is the top tight end until Olsen returns. Running back Christian McCaffrey, who leads the team in receptions with 49, will also continue to play a major role in the passing game.
At 5-3 Carolina remains in the hunt for the NFC South crown and a playoff berth, but trading Benjamin will make moving the ball tougher for Newton and an offense that has struggled for long stretches this season.
The trade was met with questions even within the Panthers' locker room: