Agnes von Krusenstjerna was born into an aristocratic family. She was educated in Stockholm and made her publishing debut in 1917 with a girl's novel. She then aroused considerable controversy by writing several sexually explicit novels, such as the series Tonybockerna ("The Tony Books") from 1922 to 1936, and the seven-volume work Froknarna von Pahlen ("The Misses von Pahlen") from 1930 to 1935. Her books ignited public debate about freedom of speech, the right of female expression, and the right to sexual freedom. Some of her work was inspired by her own life and may be partially autobiographical, especially her last, unfinished cycle of books, Fattigadel ("Poor Nobility").
Agnes von Krusenstjerna was admitted to mental hospitals on several occasions. In 1940, she was diagnosed with a brain tumor and died during surgery.