Sunday's divisional round match-up was eagerly anticipated after the AFC rivals produced a play-off classic two years ago, the Chiefs winning 42-36 in overtime.
And the rematch lived up to the hype as Patrick Mahomes and Josh Allen again had a quarterback shootout before the defending champions held on for a 27-24 win during a nervy finale.
It is the third time in four years that Kansas City have knocked the Bills out of the play-offs - and this time they did it in Buffalo.
The Chiefs will now play in the AFC Championship game for a sixth straight year and are looking to become the first team to win back-to-back NFL titles since the 2003 and 2004 seasons.
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Earlier, the Detroit Lions held off the Tampa Bay Buccaneers to win 31-23 and book a spot in the NFC Championship game for just the second time.
Both they and the Chiefs will visit the top seed in their conference next Sunday, with Kansas City taking on the Baltimore Ravens (20:00) before Detroit face the San Francisco 49ers (23:30).
After their 2022 epic, Mahomes and Allen were expected to meet many more times in the post-season and before their latest match-up, some pondered whether they could develop a rivalry like legendary quarterbacks Tom Brady and Peyton Manning.
This was Allen's best chance yet to get one over his off-season golf buddy in the play-offs as, such has been the Chiefs' recent dominance, Mahomes' 16th play-off game was his first on the road.