The deal is for an average of $7 million per season and keeps Fleury with the Golden Knights through the 2021-22 season.
"I guess you guys will be stuck with me for a little longer," Fleury said in a video posted on the team's Twitter account. "I'm really excited about it. My family and I really love Vegas, the organization, my teammates."
Fleury, 33, was 29-13-4 last season with a career-best 2.24 goals-against average and a .927 save percentage. He also posted a 2.24 goals-against average during the playoffs as he helped lead the Golden Knights to the Stanley Cup Final in their inaugural season.
A first-round draft pick by the Pittsburgh Penguins in 2003, Fleury has a career record of 404-229-70 with a 2.56 GAA and .913 save percentage.
His 404 career wins between Pittsburgh (691 games) and Vegas (46) ranks 11th in NHL history.
He won three Stanley Cups with the Penguins.