The network said Allen, the NFL's reigning Most Valuable Player, would receive a guaranteed $250 million under the terms of the six-year contract with the club, which runs through 2030.
While the Kansas City Chiefs' quarterback Patrick Mahomes signed a $450 million 10-year deal with the club in 2020, the $250 million Allen will receive is the largest guaranteed figure paid to any NFL player in the history of the sport, eclipsing the $231 million guaranteed to Dallas Cowboys quarterback Dak Prescott.
News of Allen's new deal comes after a dazzling season in which he led the Bills to AFC Championship game, where they lost to Mahomes and the Chiefs.
Last season, Allen totalled 41 touchdowns - 28 passing, 12 rushing, one receiving - as his Bills scored 30-plus points in 12 games in 2024, tied for the second-most games with 30-plus points by a team in a season in NFL history.
Allen, 28, will receive an average of $55 million per season under his new contract.
Only the Cowboys' Prescott, who earns an average $60 million a season, is paid more.