The contract is worth $73.2 million, carrying an average annual value against the NHL salary cap of $9.15 million, his agent confirmed to ESPN's Emily Kaplan.
In six seasons with the team, Barzal has 311 points in 362 games, including 91 goals. He's a two-time NHL All-Star selection.
Barzal, 25, was drafted 16th overall by the Islanders in 2015 and won the Calder Trophy as the rookie of the year in 2017-18. Barzal's 85 points were the third most of any Islanders rookie behind Hall of Famers Bryan Trottier (95 points in 1975-76) and Mike Bossy (91 points in 1977-78).
His previous contract with the Islanders was signed in January 2021 and carried a cap hit of $7 million. Barzal was in the last year of that deal and was set to become a restricted free agent next summer before committing to this new contract.
With this re-signing, the Islanders now have $71.375 million dedicated to 17 players for the 2023-24 season, according to Cap Friendly. That season's salary cap will be $83.5 million. NHL teams have been guidance by the league that the cap is projected to rise as high as $88 million in 2024-25 and $92 million in 2025-26, as the NHL recovers from its COVID-19 pandemic financial hit.