Osmond finished the season at the 2018 World Championships in Milan, Italy, where she was the defending silver medalist. She would subsequently describe the process of beginning training for the World Championships as difficult, feeling exhausted following the Olympics, but that her goal was to demonstrate that her Olympic free skate had not been a fluke. Osmond injured her ankle at her first practice session in Milan, but opted to compete. She placed fourth in the short program, following a botched double Axel. In the free skate she placed first, to finish first overall. She became the first Canadian woman to win the World Championships since Karen Magnussen in 1973 and the first Canadian woman since Magnussen to win multiple World Championship medals.