Federica Montseny Mañé was born in Madrid, Spain, to a family of anarchists. Her father was writer Juan Montseny Carret (pen name Federico Urales), and her mother was the activist Teresa Mañé Miravet (pseudonym Soledad Gustavo); they were co-editors of the anarchist journal La Revista Blanca. During her childhood, her parents returned to their native Catalonia and farmed land at the outskirts of Barcelona. Later they established a publishing company that specialized in libertarian literature. She wrote her first novel at age 15. By 18, she worked in the family business, wrote for anarchist journals under the pen name Blanca Montsan, and joined the Confederación Nacional del Trabajo (CNT) and its most radical wing, the Federación Anarquista Ibérica (FAI).
In 1936, at the start of the Spanish Civil War, she supported the republican government (a controversial position for anarchists) and was appointed Minister of Health, becoming the first woman in Spanish history to hold a cabinet job. She was known as a brilliant public speaker. In 1939, she fled the advance of fascist troops to France and led the CNT in exile until being arrested and imprisoned during World War II. After her release at the end of the war, she moved to Toulouse, where she published the anarchist newspaper, L'Espoir. She had a long relationship with fellow anarchist Josep Esgleas Jaume (alias Germinal Esgleas), with whom she had three children. She chose not to return to Spain until democracy was restored in 1977. During her long years of exile, she wrote several books, including Mujeres en la cárcel (Women in Prison, 1949), Heroínas (Heroines, 1964), and El éxodo: Pasión y muerte de los españoles en el exilio (The Exodus: Passion and Death of Spaniards in Exile, 1969). Her memoir Mis primeros cuarenta años (My First Forty Years) was published in 1987.