The convent traced its origins to a Benedictine house founded somewhere in the area during the 1100s, though its exact original location is uncertain. From 1233 the community was based at Fogdö church, which served jointly as a parish and convent church; a blocked doorway in the south wall, known as the 'nuns' door', still hints at this dual role, and the chancel was enlarged to suit the nuns' choir services. A protective charter for the convent from 1252 survives, bearing the seal of Birger jarl.
Around fifty years later, when a nearby stronghold was demolished, the nuns were allowed to move to what is now Kungsberg, where they built new, more spacious convent buildings following Cistercian planning principles. These were completed in 1289, and the community, now affiliated with Julita Abbey, took the name Vårfruberga. The convent church was a three-aisled brick-vaulted building with short transepts, divided by a low wall separating the lay sisters' area from that of the choir nuns; it is thought to have had brick facades. Historical records suggest many of the nuns came from wealthy or noble families, and surviving documents mention gifts of land made in exchange for burial rights within the convent grounds.