Iivo Niskanen made his individual World Cup debut on 12 March 2011, when he became 69th in a 20 km skiathlon in Lahti, Finland. He had his breakthrough at international level when he won the 15 kilometre classic race at the 2014 under-23 World Championships in Val di Fiemme on 30 January 2014. He won the race with a 17.4 seconds margin to Sergey Ustiugov. Only three days after he won the gold medal at the under-23 World Championships, he became 8th in a 15 km classic World Cup race in Toblach, Italy.