The Islanders finally removed all doubt about their move to Belmont Park, putting shovels into the ground on Monday, almost two years after vowing to return full time to Long Island with a new arena on the racetrack grounds.

The 19,000-seat arena (about 17,000 for hockey) is expected to be in use for the 2021-22 hockey season, ending the team’s stay in Brooklyn, which began in the 2015-16 season.

Gov. Andrew M. Cuomo, who pressed for development of the arena, participated in the groundbreaking ceremony, along with members of the team; Jon Ledecky, one of the Islanders’ majority owners; N.H.L. Commissioner Gary Bettman; and construction workers.

“The Islanders are more than a hockey team. They were a Long Island identity,” said Cuomo, who was flanked by Ledecky and Islanders captain Anders Lee as they moved ceremonial scoops of dirt with shovels that had hockey sticks for handles. “They said to Long Island, ‘You are special, you have your own team.’ There’s no place like the Islanders playing on Long Island, period.”