Magnussen's career at the elite level of skating began when she won the Canadian national junior title in 1965. Moving up to the senior level the next year, she became known for her strong free skating ability, and was even compared to then-reigning world champion Petra Burka. Her march upwards in the rankings continued as she qualified to compete at the World Championships for the first time in 1967 and won her first Canadian title in 1968. She was sent to the 1968 Winter Olympics in Grenoble, France, and placed seventh.