Leonie Sachs was born in Berlin-Schöneberg, Germany, in 1891 to a Jewish family. Her parents were the wealthy natural rubber and gutta-percha manufacturers Georg William Sachs (1858–1930) and his wife Margarete, née Karger (1871–1950). She was educated at home because of frail health. She showed early signs of talent as a dancer, but her protective parents did not encourage her to pursue a profession. She grew up as a very sheltered, introverted young woman and never married. She pursued an extensive correspondence with her friends Selma Lagerlöf and Hilde Domin. As the Nazis took power, she became increasingly terrified, at one point losing the ability to speak, as she would remember in verse: "When the great terror came/I fell dumb." Sachs fled with her aged mother to Sweden in 1940. It was her friendship with Lagerlöf that saved their lives: shortly before her own death Lagerlöf intervened with the Swedish royal family to secure their release from Germany. Sachs and her mother escaped on the last flight from Nazi Germany to Sweden, a week before Sachs was scheduled to report to a concentration camp. They settled in Sweden and Sachs became a Swedish citizen in 1952.