The Buffalo Bills suffered another devastating playoff loss under McDermott when the Bo Nix-led Denver Broncos beat the Bills 33-30 at Mile High on Saturday.
On Monday, the Buffalo Bills confirmed that they had parted ways with McDermott after nine years at the helm.
"Sean has done an admirable job of leading our football team for the past 9 seasons," team owner Terry Pegula said in a team statement.
"But I feel we are in need of a new structure within our leadership to give this organization the best opportunity to take our team to the next level. We owe that to our players and to Bills Mafia."
Sean McDermott landed in Buffalo in 2017 after spending the previous six years at the Carolina Panthers as their defensive coordinator. In his first season in charge of the Bills, the franchise ended a 17-year playoff drought, which was the longest in all of North American sports at the time.
"Sean helped change the mindset of this organization and was instrumental in the Bills becoming a perennial playoff team. I respect all the work, loyalty and attention to detail he showed for this team and the community. I wish Sean, Jamie and his family all the best," Pegula concluded.
General Manager Brandon Beane remains with the team and has been promoted, serving as both the team's GM and President of Football Operations from now on. Pegula confirmed that Beane will lead the new head-coaching search.
Standing up for Buffalo
The Bills had beaten the red-hot Jacksonville Jaguars in the Wild Card round a week prior, mostly thanks to Josh Allen's three total touchdowns and 306 yards of offense.
In Denver, though, the Bills collapsed as they committed five turnovers, four of which came from Allen, and lost after a game-winning field goal in overtime from Will Lutz.
The post-match narrative was dominated by criticism of the game officials, who threw two crucial flags on the Broncos' game-winning drive and called a crucial interception on a duel between Bills receiver Brandin Cooks and Broncos safety Ja'Quan McMillian the drive before.
In his final act as Buffalo Bills head coach, Sean McDermott called out the officiating crew in the post-game press conference.
"I've had a chance to look at it, it's hard for me to understand why it was ruled the way it was ruled," said McDermott.
After criticising the lack of replay review of McMillian's interception, an irate McDermott went off on the officials.
"I'm saying it because I'm standing up for Buffalo, damn it. I'm standing up for us. What went on, that is not how it should go down, in my estimation. These guys spent three hours out there playing football, pouring their guts out. To not even say, 'Hey, let's slow this thing down.' That's where I'm bothered."
Playoff woes
Under McDermott's reign, the Buffalo Bills became the next AFC East powerhouse after Tom Brady left the New England Patriots. The Bills won five consecutive division titles between 2020 and 2024 and made it to the playoffs in eight of McDermott's nine seasons in charge.
The Bills went 98-50 in the regular season under McDermott and saw Josh Allen win the AP NFL Most Valuable Player award in 2025 after a stellar 12-5 season.
The Bills only made it to the AFC Championship Game twice under McDermott, whose tenure was riddled with painful playoff losses despite having MVP quarterback Josh Allen as his signal-caller, losing to Patrick Mahomes and the Kansas City Chiefs in 2020 and 2024.
The Chiefs eliminated the Bills from the playoffs in four of McDermott's final six seasons in Buffalo.