Mittermaier was born on August 5, 1950 in Munich and grew up on the Winklmoosalm above Reit am Winkl, where her parents ran a ski school and a restaurant. The exceptional athlete made her debut in the 1966/1967 season. The success at the Olympic Games in 1976 was the high point and at the same time the end of her active career. In the same year, the athlete known as "Gold-Rosi" by the fans resigned as a ski racer.

She later founded a company with her husband Christian Neureuther, tried her hand as a pop singer, wrote books and was a member of the National Olympic Committee. In addition to her husband, she leaves behind her two children, Ameli and Felix Neureuther. The latter became a professional skier himself.