Pierre Brossolette was born in Paris, France. He graduated from l'École Normale Supérieure in 1925 and joined the French Socialist Party in 1929. He worked as a journalist for Notre Temps, L'Europe Nouvelle and the socialist party paper Le Populaire. He also worked for Radio-PTT but when he opposed the Munich Agreement in the air in 1939, he was fired.
When the World War Two broke out, he joined the army as a lieutenant and reached the rank of captain before the fall of France. He disapproved of the Vichy Regime and participated in founding of the resistance groups Liberation-Nord and the Organization civile et militaire in Vichy area. He later joined the Comite d'Action Socialiste. When Vichy regime forbade him to teach, Brossolette and his wife opened a bookstore in Paris. The store became a resistance meeting place.
In April 1942 Brossolette slipped to London as a resistance representative to meet Charles de Gaulle. He worked for SOE and was eventually parachuted back into Paris with Jean Moulin and F. F. E. Yeo-Thomas. Initially he opposed Moulin's Conseil National de Resistance but De Gaulle persuaded him to cooperate.
When he returned to Paris the second time, Gestapo had got his name from an arrested resistance member Rene Hardy and kept his under surveillance. He escaped arrest many times. In September 1943 he tried to return to Britain by boat but the vessel shipwrecked and Germans captured him. Initially Gestapo did not recognize him without papers but he was eventually arrested and taken to Gestapo HQ in Avenue Foch. He was heavily interrogated by torture. Afraid that he would break and reveal too much, he jumped to his death from a lavatory window in the fifth floor in Rennes Prison in Rennes, Ile et Vilaine, Brittany on March 22, 1944.