Sophia was the daughter of Richeza of Poland, Dowager Queen of Sweden, from her second marriage to a man called "Valador" King in Poloni Land. Several speculations have been put forward as to exactly who her father was, but his identity is still uncertain. It is guessed to have been Prince Volodar of Minsk or Prince Vladimir of Halicz. Most probably it was Volodar (Valadar in Belarusian) of Minsk, who united the principalities of Minsk, Polotsk, and Hrodna under his rule, and had military interests in the Baltic region (for example, his military campaign in Northern Poland in 1159).

Sophia spent a part of her childhood in Denmark, where her mother had been married to a Danish prince in her first marriage, and returned with her daughter when her second marriage was terminated. Sophia was the half sister of Canute V of Denmark, the son of her mother by her first marriage: after her half brother became king of Denmark in 1146, her mother returned to Denmark with her daughter Sophia, who thus spent part of her childhood in Denmark at the court of her half brother the king. In circa 1149, her mother married Sverker I of Sweden, in her third marriage. She took her daughter with her to Sweden, where Sophia subsequently spent the rest of her childhood at the Swedish royal court.

In 1154, at the age of circa fourteen, Sophia was betrothed to Valdemar as a symbol of alliance between Sweden and Denmark: she was at this time described as a pretty girl with promise of becoming a beauty. In the marriage contract, she was secured an eight of her half brother king Canute V:s estates in Denmark.Sophia departed Sweden for Denmark after the conclusion of the engagement in 1154, but as she was not yet regarded old enough to marry by Nordic standards, she was sent to reside with a foster mother named Bodil until she was considered old enough to live with Valdemar.The wedding between Sophia and Valdemar was conducted in Viborg in 1157, three years later. Queen Sophia was described as beautiful, dominant and cruel. According to traditional myth, she murdered Valdemar's mistress Tove and injured his sister Kirsten, but this is not confirmed.She was widowed in 1182.

As queen dowager, Sophia received a proposal from, and married, Louis III, Landgrave of Thuringia in about 1184, and was escorted to the border by her son and a grand entourage. She was repudiated in 1190, and returned to Denmark.

Sophia had the following children with Valdemar I of Denmark: Sophia (1159–1208), married Siegfried III, Count of Weimar-Orlamünde King Canute VI of Denmark (1163–1202) Maria (born c. 1165), nun at Roskilde (1188) Margaret (born c. 1167), nun at Roskilde (1188) King Valdemar II of Denmark (1170–1241) Ingeborg (1175–1236), married King Philip II of France Helena (c.1177–1233), married William of Lüneburg Richeza of Denmark (c. 1180–1220), married King Eric X of Sweden