On June 21, 2017, with the emergence of Matt Murray, Fleury willingly waived his no trade and no movement clauses to be left exposed by the Penguins 2017 NHL Expansion Draft, where he was subsequently selected by the Vegas Golden Knights. Pittsburgh also traded their second round pick in the 2020 Entry Draft as an incentive for Vegas to select Fleury, in order for the team to be relieved of his nearly $6 million cap hit. He stopped 45 of 46 shots in the Golden Knights' first NHL game, a 2–1 victory over the Dallas Stars. On October 15, 2017, Fleury was placed on Long Term Injury Reserve (LTIR) after taking a knee to the head from Anthony Mantha of the Detroit Red Wings on October 13. He was activated off LTIR on December 10, 2017, after missing 25 games. Fleury was chosen to represent Las Vegas during the 2018 NHL All-Star Game. During the NHL All-Star Weekend, he won the inaugural Save Streak competition where he saved 14 consecutive shootout attempts. On March 12, 2018, against the Philadelphia Flyers, Fleury earned his 400th career win with a final score of 3–2.