[2][3] Lagacé was transferred to the Cape Breton Screaming Eagles in 2013, where he only played eight games with a 3–3–1 record and a .887 save percentage.

Lagacé signed with the Missouri Mavericks of the ECHL in the 2014–15 season, but he was eventually traded to the Bakersfield Condors, where he would make his personal best save percentage of .915.

[4] Lagacé played two more seasons in the AHL with the Texas Stars before signing with the NHL expansion team, the Vegas Golden Knights, as a free agent in 2017.

His first National Hockey League game was on October 30, appearing in a 6–3 loss to the New York Islanders, allowing four goals on eleven shots in 25 minutes of playing time after replacing the injured Oscar Dansk.

[6] The following night, Lagacé made his first NHL start at Madison Square Garden against the New York Rangers, a 6–4 loss in which he stopped 32 of 37 shots.

[12] Lagacé stayed in the AHL until Subban suffered a lower body injury in practice during the Western Conference Final, where he was then called up to serve as Fleury's backup.

[15] Lagacé played one game during his recall, a loss to the Carolina Hurricanes on January 30, before being reassigned to the Wolves on February 8.

[19] In his debut with the Penguins on May 8, 2021, Lagacé recorded his first career shutout against the Buffalo Sabres in the final game of the regular season.

[20] Becoming a free agent the next off-season, Lagacé joined the Tampa Bay Lightning on July 28, 2021 on a one-year, two-way contract.

[21] After starting the season for AHL affiliate Syracuse Crunch, Lagacé was recalled to the Lightning on December 27, 2021, along with teammate Hugo Alnefelt.