Kristen Vadgaard grew up as the foster son of his aunt in Tandrup, Strandby in North Jutland. In 1910, he attended the teacher’s training school in Askov in southern Jutland. In 1912, Vadgaard was a member of the Danish gymnastics team that won silver behind Sweden in the Swedish system at the Stockholm Olympics.
In 1913, Vadgaard married Hanne Pihl. They had three daughters and one son. Three years later, he was a farmer in Hald Tostrup near Øls in North Jutland. From 1926-1932, he represented the Skanderborg constituency for the Venstre party in the Danish parliament over two election periods. At this time, he was a farmer in Øster-Tørslev in the Randers municipality in Central Denmark. After World War II, Vadgaard was director of a mortgage bank and member of the Vejlby-Risskov parish council in Aarhus.