He was born in Nérac, Lot-et-Garonne. He graduated from l'École Navale in 1902. During WW I he commanded an artillery battery. He remained in the navy post-war. Promoted to Rear Admiral in 1929 he was made chief of staff in 1936 and admiral of the fleet in 1937. In 1939 he was given command of the entire navy.
When Paris was occupied in June 1940, Darlan was one of those who supported Henri Philippe Pétain. He was rewarded by retaining his post as minister of the navy. He ordered the majority of the fleet to French North Africa, but fearing it would fall into German hands it was destroyed by the Royal Navy at Mers El Kébir on July 3 at the cost of around 1,300 French naval dead. This act did much to confirm Darlan's Anglophobia, but he still declined to commit the remaining vessels to German control.
In February 1941 he replaced Pierre Laval as deputy to Pétain and was also made minister for the interior, defence and foreign affairs. He was de facto head of the government. In January 1942 he gained a number of other government posts including High Commissioner in North Africa. However, the German government had become suspicious of his opportunism and "malleable loyalties" and in April he was made to surrender the majority of his responsibilities back to the more clearly pro-Nazi Laval. Darlan retained the post of Commander of the French armed forces.
He arrived in Algiers on October 2, before the beginning of Operation Torch and he accepted Allied diplomatic approaches. As the Allies landed Darlan negotiated an end to hostilities by November 10. For this he was dismissed from the Vichy government and Vichy France was 'invaded' by the German army (Operation Atilla). In return Eisenhower appointed Darlan the High Commissioner for French North and West Africa on November 14, a move that enraged Charles De Gaulle. On November 27 the remaining French naval vessels were scuttled at Toulon.
On the afternoon of December 24, 1942 a 20-year-old anti-Nazi royalist, Ferdinand Bonnier de la Chapelle, entered Darlan's headquarters in Algiers and shot him twice.
Although de la Chapelle had been a member of the resistance group led by Emmanuel d'Astier, it is believed he was acting as an individual.