Ditlevsen was born to a very poor family in a working-class neighbourhood in Copenhagen. She described her mother as being very cold and her childhood as being fragile.
She began writing poetry at the age of ten and was published by her twenties. Also, she wrote a weekly column in Familie Jornalen, answering letters from readers. Ditlevsen’s work Blinkende Lygter (Flickering Lights) was published in 1947 and became very famous.
Ditlevsen struggled with addiction to alcohol and drugs. She was admitted to the psychiatric hospital several times during her adult life. In the Dependency novel of her memoir (The Copenhagen Trilogy), she intertwines her drug use with her marriages. She was married and divorced four times.
In 1976, Ditlevsen committed suicide by overdosing on sleeping pills.