She was the daughter of Chief Verifier of the brännvin manufacturing in Sweden, August Emil Sebastian "Mille" Andersson (1843–1910) and his wife Walborg Alfhild Maria Tisell (1846-1879).

[5] Among other things, the company sold small bronze figurines, depicting children and characters from fairy tales made by her.

She spent the summers in the fishing village Briac in Bretagne where she would draw inspiration from the local fishers' life for her sculptures.

[6] She travelled back to Sweden and settled down in Islinge on Lidingö,[3] where she set up a studio which she sometimes shared with the wife of her brother Carl, Olga Milles (née Granner).

Milles got many commissions from cultural institutions in Stockholm, among them the Royal Dramatic Theatre for medallions and busts of the singer Jenny Lind and the actor Georg Dahlqvist.