Hanna Mortkowicz-Olczakowa was born in Warsaw to a literary Polish Jewish family. Her father Jakób Mortkowicz was a publisher and bookseller, and her mother Janina Mortkowicz was a writer, translator, and editor who headed the children's literature section of the family publishing house. After her father’s death in 1931, Hanna and her mother ran the publishing house for a few years. Her first published poems appeared in about 1920, when she was still a teenager. She studied Polish literature and art history at the University of Warsaw and received a doctoral degree in 1926. She wrote many novels, short stories, poems, and songs for children and young people. She survived World War II in hiding in Poland. Among her books was a biography of Janusz Korczak, the pen name of Henryk Goldszmit, the Polish Jewish physician, educator and orphanage director known as "Pan Doktor" (Mr. Doctor) who stayed with his orphans when they were sent by the Nazis to the Treblinka extermination camp. She also wrote a memoir entitled Rebellion, published in 1959.