Bills quarterback Allen barged over for two first-half rushing touchdowns at a snowy Highmark Stadium in New York as Ravens opposite number Lamar Jackson and the Bills were left ruing a string of costly errors.
The Ravens had a golden chance to tie the game with less than two minutes remaining, but tight end Mark Andrews fluffed a simple catch attempting a two-point conversion to effectively seal the Bills win.
"How about that Buffalo Bills defense?" Allen said afterwards. "All year we heard this team has no talent, we're too small, we can't stop the run? We're not good enough to compete.
"We just put our head down and worked hard - I'm so proud of our defense."
The AFC divisional round battle had been hyped as a duel between two of the most dynamic quarterbacks in the NFL, pitting this season's Most Valuable Player front-runner Allen against the Ravens' reigning MVP Jackson.
But the quarterback shoot-out largely failed to materialise in a gritty contest that ultimately pivoted on the Ravens' mistakes at key times.
A Jackson fumble following a sack by Damar Hamlin led to Allen's opening touchdown in the second quarter that put the Bills 14-7 ahead.
Allen then scored his second rushing touchdown in the closing moments of the first half to help put the Bills 21-10 up at the break.
The Ravens threatened a comeback with a field goal and a Derrick Henry touchdown in the third quarter that cut the Bills lead to three points.
But another Ravens turnover in the fourth quarter, Andrews fumbling under pressure led to a Bills field goal that stretched the hosts lead to 27-19.
Baltimore hit back with a superb Isaiah Likely touchdown from Jackson's 24-yard bullet pass, but with overtime looming, Andrews botched the two-point conversion attempt.
The Bills will now meet Patrick Mahomes and Kansas City in next week's AFC Championship game with the winner advancing to the February 9 Super Bowl in New Orleans.
It will be the latest instalment of a fierce rivalry between the two teams, who have met three times in the playoffs since 2021 -- the Chiefs winning them all.
The Bills however were one of only two teams to beat the Chiefs in the regular season this year.
"We're going to enjoy this tonight and then turn our attention to the Chiefs tomorrow," said Allen. "They're the perennial of what you want to be in the NFL. You've got to beat them to get past them."
Barkley batters Rams
Running back sensation Saquon Barkley rushed in two touchdowns as the Philadelphia Eagles beat the Los Angeles Rams 28-22 in the snow to reach the NFC Championship game.
The Eagles will host NFC East divisional rivals the Washington Commanders next Sunday for a place in the Super Bowl.
The Eagles power in the running game proved decisive in a game played in heavy snow with Barkley, a candidate for the league's Most Valuable Player, putting up 205 yards on 26 carries.
Even before the snow began to fall late in the first quarter, the Eagles exposed the Rams' run defense, opening the scoring on the opening drive of the game when quarterback Jalen Hurts broke out and sprinted 44-yards for the touchdown.
The Rams fought back quickly though with quarterback Matthew Stafford leading a 13-play, 67-yard drive which ended with a 4-yard touchdown pass to tight-end Tyler Higbee.
The Rams will have spent all week preparing for the threat of Barkley but they were still unable to stop him when he found a gap and sprinted 62 yards to put the Eagles up 13-7 at the end of the first quarter.
With conditions worsening as the snow fell heavily, the game became a gruelling battle - the Rams' second field goal of the third quarter bringing them within a point.
The Eagles extended their lead with two field goals in the fourth before Barkley turned on the turbo chargers again with 4:36 left, the snow no obstacle to his power and speed as he left as he burst 78 yards for his second touchdown.
The Rams weren't about to roll over though, with Stafford connecting with Colby Parkinson for a 4-yard touchdown pass to bring them within six points.
The Rams had one last chance, knowing a touchdown would complete their comeback and their hopes were raised when Stafford found Puka Nacua with a superb deep pass.
But with the clock against him, Stafford was unable to finish off the drive leaving the Eagles one win away from a return to the Super Bowl for the second time in three seasons.
Barkley said the snow had not dampened his enjoyment of the occassion.
"The elements were great but the atmosphere was even better. Our fans are amazing. It was a close one, but that's playoff football, and at the end of the day, we got the job done," he said.
Hurts said the conditions had taken him back to his childhood remories.
"I love playing football. Look, I used to put (snow) on when we played a video game as a kid. I'd put the snow on 100 and all that," he said.
But Hurts ended the game wearing a brace on his knee and asked about his condition said simply "I finished the game".