Selected by the Hurricanes in the second round (No. 35) of the 2015 NHL Draft, Aho arrived in Carolina in 2016-17 and finished his first season with 49 points (24 goals, 25 assists).

Aho is the third player in NHL history to begin a season (2018-19) with at least one assist in 12 straight games, joining Wayne Gretzky (Edmonton Oilers, 1982-83) and Ken Linseman (Bruins, 1985-86) and passed Ron Francis for the longest season-opening point streak in Hurricanes/Hartford Whalers history during a 3-2 loss to the Boston Bruins at PNC Arena on Oct. 30, 2018.

He had 83 points in 2018-19 and was named to the All-Star Game for the first time. Aho then helped the Hurricanes reach the Eastern Conference Final with 12 points (five goals, seven assists) in 15 playoff games.

Aho reached the 60-point mark for the fifth time in his NHL career (67 points; 36 goals, 31 assists) during the 2022-23 season while leading the Hurricanes in goals, shorthanded goals (three), shorthanded points (four) and game-winning goals (nine). He scored his 20th Stanley Cup Playoff goal during a 5-2 win against the New York Islanders in Game 4 of the 2023 Eastern Conference First Round to pass Eric Staal for the most in franchise history.

He had 89 points (36 goals, 53 assists) in 78 games in 2023-24. He had 12 points (four goals, eight assists) in 11 playoff games, joining Wayne Gretzky and Mario Lemieux as the third player in NHL history to finish at least tied for his team's scoring lead in each of his first six postseasons.

Aho played for Finland at the 4 Nations Face-Off and won bronze with Team Finland at the Olympic Winter Games Milano Cortina 2026. He led the team with four goals that were tied for second in the tournament and opened the scoring in Finland's 6-1 win against Team Slovakia to help secure the bronze. Prior to his Olympic debut, Aho became the fourth Finland-born player in NHL history with 10 seasons of at least 20 goals, after Teemu Selanne (17), Jari Kurri (13) and Aleksander Barkov (10).

Aho became a restricted free agent after the season and signed a five-year, $42.27 million offer sheet with the Montreal Canadiens on July 1, 2019. The Hurricanes matched the offer July 7.