Klæbo participated in his first Olympics at the 2018 Winter Olympics in PyeongChang, South Korea. Prior to the Olympics, he had nine victories in the 2017–18 World Cup. He made his Olympic debut by finishing 10th in the men's skiathlon event. On 13 February 2018 he became an Olympic champion after winning the men's sprint. This victory made him the youngest ever male to win an Olympic event in cross-country skiing. He skied the last leg on the Norwegian teams that won both the 4 × 10-kilometre relay and the men's team sprint. A steep hill on the Olympic course was dubbed "Klæbo-bakken" ("Klæbo hill") by Norwegian media after Klæbo overtook his competitors several times in this climb throughout the games. With three gold medals, he tied with French biathlete Martin Fourcade for most gold medals won in the games.