Rossi first played ice hockey in his native Austria when he was 3 years old. At the age of 10 Rossi moved to
Switzerland to further his career, and Feldkirch, his hometown, is close to the
Austria–Switzerland border. At the age of 13 Rossi moved to
Zürich again to help his career, with him and his father commuting two hours each way in order to allow Marco to stay at home and continue his education. He played in the junior system of Switzerland within the system of the
ZSC Lions, frequently playing in older age categories. He made his professional debut in the
2017–18 season, playing 18 games and recording seven points for the
GCK Lions of the
Swiss League, the second-highest league in Switzerland. After the season he was selected 18th overall by the
Ottawa 67's of the
Ontario Hockey League (OHL) in the
CHL Import Draft. He played 53 games with Ottawa in
2018–19 and scored 65 points, finishing fourth on the team in scoring, and had an additional 22 points in 17 playoff games. Rossi was named to the OHL Second All-Star Team as a result. Rossi returned to Ottawa for the
2019–20 season and led the OHL, and the entire CHL in scoring with 120 points in 56 games. He was awarded the
Eddie Powers Memorial Trophy and
CHL Top Scorer Award for leading the OHL and CHL in scoring, respectively, and was named the most outstanding player in the OHL, winning the
Red Tilson Trophy, and was also named to the OHL's First All-Star Team. He was the first European player to lead the OHL in scoring (
Stan Mikita, who was born in Slovakia and raised in Canada, did so in the
1958–59 season). Heading into the
2020 NHL entry draft, Rossi was regarded as a top prospect, and the
NHL Central Scouting Bureau had him ranked as the sixth-best North American-based skater for the draft. He was selected in the first-round, ninth overall, by the
Minnesota Wild. On 23 October 2020, Rossi was signed by the Wild to a three-year, entry-level contract. Five days later, he was loaned to the ZSC Lions until the start of NHL training camp. He held a Swiss player-licence after having played most of his junior career in Switzerland, but only played one game for ZSC Lions. The NHL delayed the start of the
2020–21 season until January 2021, and Rossi was invited to join the Wild's training camp prior to the season starting. However, he returned to Austria due to long-term complications from
COVID-19; he had tested positive late in 2020 for the virus. Speaking about his battle with the virus, Rossi stated: "I'm thankful to God that he supported me. ... I'm just happy that I'm still alive."
Minnesota Wild Rossi started the 2021–22 season with Minnesota's minor league affiliate, the
Iowa Wild of the
American Hockey League (AHL). After playing 21 games in the AHL, where he scored 23 points, Rossi was recalled to Minnesota in January 2022, and made his NHL debut on 6 January 2022, against the
Boston Bruins. He played two games in the NHL before returning to Iowa. On 22 August 2025, Rossi, a
restricted free agent, signed a three-year contract with the Wild.
Vancouver Canucks On 12 December 2025, Rossi was traded to the
Vancouver Canucks along with
Liam Öhgren,
Zeev Buium, and a
2026 first-round draft pick, in exchange for
Quinn Hughes. ==International play==