Beniers was the first-ever NHL Draft pick of the expansion Seattle Kraken when he was chosen No. 2 in the 2021 NHL Draft. He agreed to a three-year contract with the Kraken on April 10, 2022, after two seasons at the University of Michigan, and had an assist in 17:10 of ice time in his NHL debut, a 5-3 loss at the Calgary Flames on April 13, 2022. Beniers had a goal and two assists to become the first Seattle rookie with a three-point game and help the Kraken score eight goals for the first time in their history in an 8-5 win against the San Jose Sharks at Climate Pledge Arena on Nov. 23, 2022.

He won the 2022-23 Calder Trophy, given annually to the best rookie in the NHL as voted on by the Professional Hockey Writers Association, after leading first-year players in points (57) and plus-minus rating (plus-14), tied for the NHL lead in goals with Wyatt Johnston of the Dallas Stars (24) and ranking second in assists (33) in 80 games for the Kraken, who clinched a berth in the Stanley Cup Playoffs in their second NHL season. Beniers turned 20 during the season and was youngest Calder recipient since Elias Pettersson of the Vancouver Canucks (age 20 in 2018-19).

Beniers struggled in his second full NHL season, scoring 37 points in 77 games, but the restricted free agent was still rewarded with a seven-year, $49.98 million contract on Aug. 20.

Beniers led Michigan with 43 points (20 goals, 23 assists) and 10 power-play goals in 37 games in 2021-22, when it lost 3-2 in overtime to Denver in the NCAA Frozen Four semifinal round. Beniers scored 67 points (30 goals, 37 assists) in 61 games and was the third scoring champion for Michigan in Big Ten history, joining Kyle Connor (2016) and Cooper Marody (2018).

Beniers had three points (one goal, two assists) in seven games to help the United States win the 2021 IIHF World Junior Championship and played one game in the 2022 WJC before the tournament was postponed due to concerns surrounding the coronavirus. He had one goal and one assist in four games at the 2022 Beijing Olympics, where at age 19 he was the youngest player on a team with 15 NCAA players and 10 older teammates, the latter with NHL and European pro leagues experience. He averaged the most ice time among forwards (19:39 per game).