Hirvonen, who started for Jyvaeskylae SC , made his international debut in mid-December 2013 at the Continental Cup competition in Soldier Hollow , but missed the points. It was not until March that he was able to get Continental Cup points for the first time when he reached 20th place in his home town of Kuusamo . At the end of the season two days later he achieved his best result of the season with sixth place in the Gundersen competition on the large hill and over 15 kilometers.
In the 2014/15 season , Eero Hirvonen made his debut on March 6, 2015 in Lahti in the Nordic Combined World Cup . At the Gundersen competition on the large hill, he finished 33rd. In the 2015/16 season , Hirvonen was able to collect World Cup points for the first time in an individual competition on February 19, 2016 when he took 25th place at the Gundersen competition on the large hill in Lathi. At the end of the season, Hirvonen was 56th overall.
In his third participation in a Junior World Championship in 2016 , Hirvonen finally won his first medal with the team in Râşnov, Romania . A few days earlier he had missed an individual medal in fourth in the Gundersen competition over 10 km.
In winter 2016/17 he was able to achieve his first top ten place as well as his first podium. At the Gundersen competition on the large hill in Kuusamo on November 26th, 2016, he took seventh place and on January 7th, 2017, at the same competition in Lahti, he finished second behind the German Eric Frenzel . At the Nordic World Ski Championships 2017 in Lahti, he took ninth place on the normal hill and 21st place on the large hill. Together with Leevi Mutru , Ilkka Herola and Hannu Manninen , he placed fifth in the team competition, while he finished seventh in the team sprint together with Herola.
Herola took part in the Winter Olympics in Pyeongchang in February 2018 , where he finished sixth both in the two individual competitions and with the team.
On February 9, 2019, he won a World Cup competition for the first time in the team sprint in Lahti, Finland, together with Ilkka Herola. Two weeks later it was only seventh in this discipline at the Nordic World Ski Championships 2019 in Seefeld .
Finland
2018 Pyeongchang
2019 Seefeld
