Bjørnøy graduated from MF Norwegian School of Theology in 1980 and was ordained a minister in the Church of Norway the same year. She held a teaching position as assistant professor in the field of Ethics at Lovisenberg Deaconal University College from 1991 to 1999. Her last position before entering into government was Secretary General for the Church City Mission, Kirkens Bymisjon (1999–2005).