The scion of an aristocratic Austrian family, Henreid first worked as a designer and translator at a Vienna publishing firm until he was discovered in an acting school performance by Otto Preminger, who was then Max Reinhardt's managing director. Henreid became a leading man with Reinhardt's theater company and appeared in two Austrian films in the early 1930s before he moved to England because of his anti-Nazi sentiments. There he starred on the London stage and in films, ironically being cast as a Nazi officer in "Madman of Europe" and as a Gestapo agent in Carol Reed's "Night Train" (both 1940). Moving to the US in 1940, he was again cast as a German in the Broadway production "Flight to the West".
Signing with RKO Radio Pictures in 1941, Henreid played his first heroic role as a Free French R.A.F. pilot in his Hollywood debut, "Joan of Paris" (1941). It was the first of many films in which he would dramatize the wartime plight of sympathetic Europeans.
In the 50s Henreid starred in mediocre swashbucklers such as "Last of the Buccaneers" (1950) and "Thief of Damascus" (1952), and melodramas like "So Young, So Bad" (1950) and "Stolen Face" (1952). With his career as a romantic lead petering out he switched to producing and directing, especially on TV, where he directed numerous episodes of "Alfred Hitchcock Presents", "The Schlitz Playhouse", "G.E. Theater", "Maverick" and "Bracken's World". In 1964, Henreid reteamed with his "Now, Voyager" and "Deception" (1946) co-star Bette Davis, directing her in the dual roles of homicidal twin sisters in the campy suspense melodrama "Dead Ringers".