The 21-year-old was born in Jyväskylä, Finland. Before his selection by the Anaheim Ducks in round two of the 2015 entry draft, he spent time in the Ontario Hockey League with the Barrie Colts and the Windsor Spitfires. Over those two years, regular season and playoffs, he collected 38 goals and 83 assists.
Last season, Nattinen and the Windsor Spitfires won the Mastercard Memorial Cup, the Canadian Hockey League’s biggest prize. He also played in the World Junior Championships (WJC) for Finland twice. In 2016, he was part of Finland’s gold medal-winning team, chipping in with a goal and two assists.