Career
He is currently playing for the San Antonio Rampage in the American Hockey League (AHL) as a prospect for the Colorado Avalanche of the National Hockey League (National Hockey League). He was selected in the first round, 10th overall, by the Avalanche in the 2015 National Hockey League Entry Draft. Rantanen made his professional Finnish Master of Science-liiga debut as a 16-year-old playing with The Human Context TPS during the 2012-2013 season.
Rantanen had played with TPS from a youth of 14-years old at the under-16 level
In 15 games he impressively scored 2 goals and 3 points. Entering the 2014-2015 season as the only 17-year-old to play in his third year with TPS, Rantanen signed a two-year extension to remain with the Liiga outfit on October 9, 2014.
Through using his big frame and physical play, Rantanen recored career high 9 goals and 28 points in 56 games, also serving as an Alternate captain. In his National Hockey League draft eligible year, he was subsequently rated as the top European skater at season"s education
He was the first European based player selected when he was taken 10th overall by the Colorado Avalanche at the 2015 National Hockey League Entry Draft on June 26, 2015.
On July 13, 2015, Rantanen was signed to a three-year, entry-level contract with the Colorado Avalanche. After attending his first Avalanche training camp, and impressing in the pre-season, Rantanen was announced to have made the opening night roster for the 2015-2016 season as an 18-year old on October 6, 2015. On October 8, 2015, Rantanen made his National Hockey League debut to open the season with the Avalanche in a 5-4 defeat to the Minnesota Wild.
Rantanen was used in a depth role and played limited minutes over six scoreless games with Colorado before he was sent to AHL affiliate, the San Antonio Rampage on October 22, 2015.
Rantanen was introduced and developed as a youth in the Finnish national junior under-16 program He was first selected at an international tournament at the 2013 World U-17 Hockey Challenge, tallying 7 points in 5 contests.
He went on to lead the team at the under-18 level with 7 points in 4 games at the 2013 Ivan Hlinka Memorial Tournament before competing in his first full IIHF competition at the 2014 IIHF World U18 Championships. Rantanen continued his progression within the Finnish junior team in earning selection to the 2015 World Junior Championships in Toronto, Canada.
Despite a disappointing seventh-place finish, Rantanen contributed with 4 goals in 5 games to earn a top 3 player on team selection.
During his first North American professional season and while eligible for his final junior tournament, Rantanen was loaned by the Colorado Avalanche to Captain the Finnish junior team as they hosted the 2016 World Junior Championships. While adding a stabilising veteran presence, Rantanen played a supporting role throughout the round-robin stage before stepping up his production in the Semi-final against Sweden and scoring in the Final against Russia to help Finland claim the gold medal and cap his junior career.