Rasmus Dahlin, Ryan McLeod, and Jason Zucker scored in regulation for the Sabres. Ukko-Pekka Luukkonen made 16 saves and stopped two out of three Vegas shooters in the tiebreaker.
The Sabres had dropped seven of eight.
Jack Eichel, Brett Howden, Pavel Dorofeyev scored for the Golden Knights, who lost for the third time in four games. Adin Hill made 34 saves in regulation and overtime.
Vegas grabbed a 3-2 lead when Eichel scored with 2:33 left in the third. It was Eichel’s 21st goal of the season.
Dahlin responded with his 12th goal for Buffalo with 13.6 seconds to play.
Sabres forward Jiri Kulich was injured at 9:25 of the second period after a hit from Howden.
Sabres: Playing without forwards J.J. Peterka and Josh Norris, Buffalo still outshot Vegas 37-21. Norris, who was acquired from Ottawa at the trade deadline, was out with an undisclosed injury.
With Luukkonen pulled for the extra attacker, Dahlin’s slap shot from the blue line whistled past Hill and sent the game to overtime.
Dahlin became the first Sabres defenseman to tie a game in the last minute since Tyler Myers on Jan. 18, 2014, against Columbus.
The Sabres begin a four-game trip in Boston on Monday. The Golden Knights face the Red Wings on Sunday in Detroit.
