Kupari made his professional and Liiga debut with Kärpät in the 2017–18 season on 14 September 2017.

On 22 June 2018, Kupari was selected in the first round, 20th overall, by the Los Angeles Kings in the 2018 NHL Entry Draft.

[3] On 27 June 2023, Kupari was traded with Gabriel Vilardi, Alex Iafallo, and a 2024 second-round draft pick to the Winnipeg Jets for Pierre-Luc Dubois.

[4] As a restricted free agent, Kupari agreed to terms with the Jets in signing a two-year, $2 million contract extension on 2 August.

This biographical article relating to a Finnish ice hockey centre is a stub.