Born in Walloon Brabant, Martha Grünenwaldt spent her childhood playing the violin to accompany her father, a traveling musician, and attended school very little. Married at twenty-three to a musician, she worked in a factory until the birth of her daughter. After four years of marriage, she left the household with her child and led a wandering life, playing the violin at café terraces.
In 1940, her husband regained custody of their daughter. Martha Grünenwaldt then found work as a domestic in a castle, where she was forbidden to touch her instrument. In 1968, her daughter invited her to live with her.
It was not until the age of seventy-one that she began drawing. Often working on the back of posters and reclaimed wallpaper, she depicted exclusively female figures that transform into flowers and animals.