Kunin, a forward born in Chesterfield, Missouri, was chosen by the Minnesota Wild with the No. 15 pick in the 2016 NHL Draft.

He had to overcome being diagnosed with Type I diabetes while in the sixth grade. After attending Whitfield School in Missouri for one year, he joined the USA Hockey National Team Development Program and graduated from high school in three years.

Kunin played two seasons at the University of Wisconsin. His nine goals in 2015-16 were third among NCAA freshmen. The following season, he became the second sophomore captain in school history and the first since Mike Eaves 40 years earlier. Kunin led the Badgers with 22 goals and 38 points in 35 games, to make the All-Big Ten Second Team.

His college career ended when he signed a three-year contract with the Wild on March 23, 2017, and he scored his first NHL goal in a 6-4 win against the New York Islanders on Oct. 26, 2017, becoming the first player in Wild history to do so while shorthanded.

Kunin was sent back to the American Hockey League on Oct. 29. He represented Iowa at the 2018 AHL All-Star Game and was recalled by Minnesota on Feb. 28, 2018. However, his season ended with a torn ACL in his left knee sustained in a game against the Detroit Red Wings on March 4.

Injuries slowed Kunin in 2018-19, but he became a regular in 2019-20 and had NHL career highs in goals, assists and points. He was traded to the San Jose Sharks on July 8, 2022, and signed a two-year contract 10 days later.

Kunin re-signed with the Sharks on June 30, 2024 (one year, $2.75 million), after he had 18 points (11 goals, seven assists) in 77 games, the fourth time in his NHL career he reached double-digit goals. He led Sharks forwards with 165 hits and played his 300th NHL game at the Vancouver Canucks on Nov. 20. Kunin was also San Jose's nominee for the King Clancy Memorial Trophy in 2023 and '24. He established the Luke Kunin T1D Fund in 2021 to be an ambassador for kids living with Type 1 Diabetes to help raise money that directly benefits the Juvenile Diabetes Research Foundation (JDRF).

Kunin was traded to the Columbus Blue Jackets by the Sharks on March 7, 2025, 63 games into the season. He signed a one-year contract with the Florida Panthers on Aug. 22.