Hadalin made his World Cup debut on March 8, 2014 in the giant slalom in Kranjska Gora . After he narrowly missed the points ranks twice, he classified himself in the top 30 for the first time in January 2016 as 26th in the Wengen slalom , but did not win any World Cup points due to the lack of time. He succeeded in December of the same year as 23rd in the combination of Santa Caterina . He achieved further top results with ranks 20 and 15 in the slaloms of Adelboden and Wengen . At the World Championships in St. Moritz , he started in four competitions. In the slalom, he achieved the fastest time in the second run and took a strong tenth place.
With two 16th places Hadalin traveled to the Winter Olympics in Pyeongchang , where he recorded four starts. After he achieved his best result in a major event in combination with eighth place, he finished 21st in the giant slalom and retired in the first run in the slalom. With the Slovenian team, he finished tied for ninth place. In December 2018, he managed to jump to eighth place in the slalom of Saalbach with a best runner-up in the second round and thus his first top 10 result in the World Cup. At the World Championships in Åre he managed to win the silver medal after downhill rank 30 with the fastest time in slalom. In doing so, he secured the first men's medal for a Slovenian since Mitja Kunc in the 2001 slalom. A few days later, he was on a World Cup podium for the first time in the combination of Bansko .