Bills running back Marshawn Lynch was traded to Seattle on Tuesday, and the Seahawks made room for him by releasing Julius Jones.
The Bills said they will receive undisclosed draft picks for Lynch.
Buffalo's move to deal Lynch clears the way for more playing time for Fred Jackson and first-round draft pick C.J. Spiller.
Jones led the Seahawks (2-2) in rushing the last two seasons.
The Seahawks have a bye week following their 20-3 loss to the St. Louis Rams. Buffalo (0-4) lost to the New York Jets 38-14 and plays host to Jacksonville on Sunday.
While Seahawks new coach Pete Carroll is looking to retool his running game, the Bills have a much larger rebuilding job. Last week, new coach Chan Gailey released former starting quarterback Trent Edwards, who is now with the Jaguars.
Seattle's run game has struggled through four games, ranked 27th with 79.5 yards per game. In three games, the Seahawks had under 80 yards rushing.
Without a clear No. 1 back, the Seahawks ran by committee before settling on the speedy Justin Forsett. Forsett had a season-high 19 carries Sunday against St. Louis, but managed only 65 yards.
Jones was inactive against the Rams, while special teams sensation Leon Washington has just 12 carries for 30 yards.
Seattle hasn't seen a back approach 1,000 yards since Shaun Alexander was the league MVP in 2005 after running for 1,880 yards and 27 touchdowns in the Seahawks NFC championship season.
Lynch is reunited with Forsett -- the two played together at California.
"Marshawn's excited to go to the west coast, but is very appreciative of the time he had in Buffalo," the player's agent Doug Hendrickson said. "It's bittersweet, because he wishes it would've worked out better in Buffalo."
After losing his starting job to Jackson last season, Lynch reclaimed the job in Week 2 this year and led the Bills with 37 carries for 164 yards. In 45 career games, he has 2,765 yards rushing and 17 touchdowns, along with 670 yards receiving and a score.
The deal was made two weeks before the NFL trade deadline, and marks a turnaround in philosophy for the Bills, who said last spring they had no intention of trading him. Lynch had been seeking a fresh start after his reputation in Buffalo took a hit following his off-field troubles.
In June 2008, he pleaded guilty to a traffic violation and admitted to driving off after striking a female pedestrian with his car near Buffalo's downtown bar district.
In March 2009, Lynch pleaded guilty to a misdemeanor gun charge in Los Angeles, after police discovered a semiautomatic handgun in a backpack of the trunk of a parked car Lynch was sitting in.