Born on 18 September 1932 in Aalborg, Karen Horsens was one of the three daughters of the bicycle retailer Alfred Horsens (1897–1971) and Karla Kristensen (1900–1989). On matriculating from Aalborg Cathedral School in 1951, she decided to study theology which at the time was an unusual choice for a girl. In 1957, she became the first woman theologian to receive Aalborg University's gold medal for a dissertation on Bishop Peder Madsen. On graduating as Cand.theol. in 1958, she continued her studies abroad, first in Oslo and later in New York on a fellowship from the American Association of University Women.[1]
In 1962, she was appointed a chaplain at the Church of Our Saviour in Copenhagen. It was here she met the organist Charley Olsen whom she married in 1968. They have one son together, Rasmus. She remained at the church for 20 years, becoming the parish priest in 1972.[1]
Horsens became a board member of the clerical association Den Danske Præsteforening in 1974, becoming its chair from 1978 to 1982. She was an effective leader, campaigning for better salaries and working conditions for priests.[1] In 1990, she published her sermons, which have since been frequently cited.[2]
Since her husband died in 2011, Karen Horsens has been living as a widow in a small pensioner's home close to Roskilde Cathedral.[3]