Sonja Edström-Ruthström belonged to the elite cross country skiers of the late 1950s and early 1960s. She took part in the first ever women's Olympic event in cross-country skiing at Oslo in 1952. In 1956 at Cortina d’Ampezzo she took bronze medals in both ladies events, the individual 10 km as well as the 3x5 km relay. Sonja Edström also ran the third leg with the Swedish relay team that won gold in 1960 in Squaw Valley together with Irma Johansson and Britt Strandberg. She also won two 3x5 km bronze medals at the FIS Nordic World Ski Championships in 1954 and 1958. One of her biggest individual successes was victory in the 10 km at the 1956 Holmenkollen Ski Festival. Between 1953 and 1960, she won a total of 12 individual Swedish Championships and three in the relay, achieved three victories in the Swedish Ski Games in Falun and one in the Lahti Games.
When Sonja Edström was six-years-old, her mother fell seriously ill and her father was left alone with six young children. When she was 14, she began working as a maid. Two years later she got a job washing empty bottles at the Luleå Brewery. For more than 30 years she worked at the hospital in Luleå as a nursing assistant and started competing as Edström-Ruthström in 1960.