Finland Matinpalo made his
Liiga debut with
Ilves during the
2018–19 season. He made 30 appearances for Ilves in the regular season, scoring two
goals and four
assists for six
points. He also appeared in two games for
KooVee Tampere of
Mestis going scoreless. Matinpalo made seven playoff appearances, going scoreless. He began the
2020–21 season with Ilves and made 11 appearances, going scoreless. He also played one game for KooVoo Tampere. In 30 games with Ässät to finish the season, he marked one goal and three points. In his final year with the team in
2022–23, he set new career highs with 51 appearances, with seven goals and 16 points. In eight playoff games, Matinpalo tallied four assists. He attended the 2023 Senators training camp but did not make the team. He was assigned to Ottawa's
American Hockey League (AHL) affiliate, the
Belleville Senators, to begin the
2023–24 season. After injuries to
Thomas Chabot and
Erik Brännström, Matinpalo was recalled by Ottawa on 28 October. He played in his first NHL game the same day, a 5–2 win over the
Pittsburgh Penguins. He was returned to Belleville after four games with Ottawa on 10 November. Matinpalo spent the rest of the season with Belleville, playing in 67 games, scoring four goals and 14 points. He passed through
waivers, going unclaimed, and was assigned to Belleville to start the
2024–25 season. He was recalled to Ottawa on 28 December as an injury replacement for
Artem Zub. He made his season debut on 29 December in a 3–1 victory over the
Minnesota Wild. He was briefly returned to Belleville on 3 January 2025 before being recalled again on 7 January. He made 24 appearances for Belleville, tallying two goals and eight points. He recorded his first NHL goal in a 4–0 victory over the
Columbus Blue Jackets on 6 April. The Senators qualified for the
playoffs, facing the
Toronto Maple Leafs in the opening round. He made his playoff debut on 20 April. The Senators were eliminated in six games in their best-of-seven series. In the series, Matinpalo went scoreless. == International play ==