Jim Härtull made his debut on November 29, 2008 at the World Cup in Kuusamo in the Nordic Combined World Cup . After jumping he was in 41st place and ended the race in 57th and last place. Despite poor performance in the World Cup, he was nominated for the Nordic World Ski Championships in Liberec in 2009. After he only finished 51st in the individual competition, he was allowed to compete in the team competition with Jaakko Tallus , Lauri Asikainen and Janne Ryynänen . The Finnish quartet finished the competition in eighth place. In the following season, Härtull missed the qualification for the 2010 Olympic Winter Games in Vancouver .
On November 26th, 2011 Jim Härtull was able to collect his first World Cup points at the World Cup in Kuusamo . After jumping he was in 17th place and was able to finish the race in 24th place. With that he collected his first seven World Cup points. On March 10, 2012 he started in the Continental Cup of Nordic Combined 2011/12 together with Eetu Vähäsöyrinki in the team sprint at the Continental Cup in Kuopio . The Finnish duo only had to admit defeat to the Austrian duo. At the end of the season he finished 49th in the overall Nordic Combined World Cup, which is her best result in his career.
After Jim Härtull was able to collect his last World Cup points in the 2011/12 season, he again collected World Cup points at the World Cup in Sapporo on January 23 and 25, 2015. In the first competition, he finished 21st, his best result in the World Cup. He had previously occupied this place at the World Cup in Klingenthal in the 2011/12 season. In the second competition in Sapporo , he again collected World Cup points with 28th place. He was nominated by Suomen Hiihtoliitto for the Nordic World Ski Championships 2015 in Falun and was allowed to compete in all four competitions there. While in the individual only the 29th place on the normal hill and 27th on the large hill took place, he surprised together with Ilkka Herola as fourth in the team sprint. The Finnish team, which consisted of Leevi Mutru , Eetu Vähäsöyrinki , Ilkka Herola and himself, had to be content with ninth and penultimate place. After failing to qualify for the home World Cup in Lathi in 2017, he ended his active career.