Kiviranta became an instant hero for the Dallas Stars in his first trip to the Stanley Cup Playoffs. After being scratched for the first six games of the Western Conference Second Round against the Colorado Avalanche, the forward from Vantaa, Finland, completed a hat trick by scoring in overtime to give the Stars a 5-4 victory and their first trip to the Western Conference Final since 2008.

He also scored in Game 5 of the conference final, helping the Stars eliminate the Vegas Golden Knights, and again in Game 1 of the Stanley Cup Final against the Tampa Bay Lightning.

Kiviranta was never drafted by an NHL team. He signed a two-year, entry-level contract with the Dallas Stars on May 31, 2019, after impressing them with his performance at the IIHF World Championship that spring. He had three points (two goals, one assist) to help Finland win the tournament, and scored the game-winner against France in the preliminary round.

Kiviranta came to North America from Vaasan Sport in Liiga, Finland's top professional league. He scored 114 points (60 goals, 54 assists) in five seasons with Vaasan Sport, including 31 points (16 goals, 15 assists) in 48 games in 2018-19, when he finished second on the team with a plus-12 rating. He scored a team-high 37 points (19 goals, 18 assists) in 2017-18.

After signing with the Stars, Kiviranta started the 2019-20 season with Texas of the American Hockey League and, after scoring six goals in December, made his NHL debut against the Detroit Red Wings on Jan. 3, 2020. Coincidentally, he did so in front of his parents, who were visiting from Finland and had asked him for tickets for that game without knowing he'd be called up to the Stars. He scored his first NHL goal Feb. 1, 2010, at the New Jersey Devils.

Kiviranta played 56 games for the Colorado Avalanche in 2023-24, earned a one-year contract through the 2024-25 season and another he signed for 2025-26 on Aug. 8. He helped Team Finland win bronze at the Olympic Winter Games Milano Cortina 2026.