Valdemar (English: Waldemar; Swedish: Valdemar Birgersson), was King of Sweden from 1250–1275.
Valdemar was the son of Princess Ingeborg Eriksdotter of Sweden and Birger Jarl, from the House of Bjelbo. During the first sixteen years of his reign, it was Birger Jarl who was the real ruler. Birger Jarl had in fact been the de facto ruler of Sweden from 1248, before the reign of Valdemar, under King Eric XI of Sweden. Valdemar's mother was a daughter of King Eric X of Sweden and Princess Richeza of Denmark.
When King Eric XI died in 1250, Valdemar was elected king. Even after the coming of age of Valdemar in 1257, Birger Jarl held a grip over the country. After Birger's death in 1266 Valdemar came into conflict with his younger brother Magnus Birgersson, Duke of Södermanland, who wanted the throne for himself.
In 1260, Valdemar married Sofia of Denmark the eldest daughter of King Eric IV of Denmark and Jutta of Saxony. Valdemar also had a relationship with his sister-in-law Jutta of Denmark. In 1272, Jutta visited Sweden and became Valdemar's mistress. The affair resulted in a child born in 1273. The following year, Jutta was placed in a convent and Valdemar was forced to make a pilgrimage to Rome to ask for the absolution of the Pope.
Valdemar was deposed by his younger brother, Magnus after the Battle of Hova in Tiveden June 14, 1275.