Vilhelmine Ullmann, née Dunker, was born and grew up in Christiania. Her mother was the writer and school principal Conradine Dunker, who took her daughter's education into her own hands. She supported herself as a governess until she married in 1839. After fifteen years of marriage and six children, she separated from her husband. She went on to establish a girls' school and later ran a day nursery until she was seventy-eight years old.
From 1887 she wrote under the pen name M. D. (Minna Dunker) for the women's periodical Nylænde, made her debut with the children's tale Spillerbakken og Bjørnen in Nordisk Illustreret Børneblad, 1874-1875, and in 1903 at the age of eighty-seven published her memoirs, Fra Tyveaarene og lidt mere.