Born into the Camondo family of Paris, she was the daughter of Moïse de Camondo and Irène Cahen d'Anvers, both of whom were from prominent Jewish banking families. One of two children, her older brother Nissim served as a fighter pilot during World War I and in 1917 was killed in action.
- Fanny (born 26 July 1920 in Paris - died in 1944)
- Bertrand (born 1 July 1923 in Paris - died in 1944)
On her father's death in 1935, Béatrice inherited a large fortune. Her father bequeathed his Paris home, including its contents and a major collection of art, to the Musée des Arts Décoratifs to be used to create the Musée Nissim de Camondo in his son's honor.
A convert to Catholicism, Beatrice Camondo Reinach felt safe in Paris after the Nazi occupation. Divorced from her Jewish husband Leon Reinach, she believed her wealth and the influential people she rode horses with in the Parc Monceau would shield her from being taken. In the Musee Nissim Camondo, on the top floor, is a letter from her ex-husband telling Beatrice to leave Paris with their son and daughter. She disregarded his advice. In 1943, under the German occupation of France during World War II, Béatrice, her husband and their two children were forcibly removed from their Paris home and taken to the Drancy deportation camp north of the city. From there, they were deported to Auschwitz concentration camp where they were all killed.
- Steinbach, Alice (August 15, 2004). "Past, Prologue and Paris". The New York Times.
- Michlin, Gilbert (2004). Of no Interest to the Nation: A Jewish Family in France, 1925-1945. Wayne State University Press. p. 122. ISBN 978-0-8143-3227-6.
- Birnbaum, Pierre (1996). Les Fous de la République. Stanford University Press. p. 9. ISBN 978-0-8047-2633-7.