Svantepolk's father was Canute, Duke of Revalia, a bastard son of king Valdemar II of Denmark with a high-born Swedish lady Helena, daughter of Earl Guttorm. His mother had been a Pomeranian lady whose first name and precise origin is not known to us, but who is indicated to have come from the ducal family of Pomerelia. Svantepolk's brother was Eric, Duke of Halland who died in 1304.
Svantepolk settled in Sweden in the mid-13th century. His wife was Benedikte of Ymseborg, daughter of (Earl) Sune Folkesson, a grandson of earl Birger Brosa. Benedikte's mother was Helena Sverkersdotter, the daughter of king Sverker II of Sweden and his first wife Benedikte Ebbesdatter of the Galen family of Denmark. Benedikte's elder sister Catherine of Ymseborg was wife of king Eric XI of Sweden (1216-50), so Svantepolk was the late king's brother-in-law.
Svantepolk and Benedikte's daughters married lords of Swedish high nobility and became ancestresses of several Swedish noble families, substantial dowries following. Lord Svantepolk, with royal ancestry and rights to ducal dignity of Halland and Revalia, was a valued ancestor, well-remembered in his noble Swedish descendants' pedigrees and family lore. The name Svante, a shortened version of Svantepolk, was given to many Swedish descendants.