Mowinckel had her breakthrough in the 2018 season, taking her first podiums: third place in Super-G in Val d'Isère and runner-up in giant slalom in Kronplatz. At the Winter Olympics in Korea, Mowinckel surprisingly won two silver medals in Giant Slalom and Downhill; she also finished fourth in combined and 13th in Super-G. Her first World cup win came in giant slalom in Ofterschwang in March 2018, edging home favourite Viktoria Rebensburg.