When Armendáriz finished his studies, he moved to Mexico where he worked for the railroad, as a tour guide and as a Journalist for the bilingual magazine México Real. He was discovered by film Director Miguel Zacarías when Armendáriz recited a soliloquy from Hamlet to an American tourist. His meeting with the Director Emilio Fernández was providential. Actor and Director began working in numerous films: Soy puro mexicano (1942), Flor silvestre (1942) and specially María Candelaria (1943) were the first films of intense Common path. Under the guidance of Emilio Fernández, Pedro Armendáriz developed the film personality traits of strong nationalist; often, he played tough and manly men, indigenous, peasants and Revolutionaries. Amendáriz repeatedly portrayed Pancho Villa and played opposite actresses such as Dolores del Río and María Félix.
With Dolores del Río, Amendáriz formed one of the most legendary couples of the Mexican cinema. María Candelaria provided Armendáriz with international visibility. The film was awarded the Palm d'Or at the 1946 Cannes Film Festival. Other prominent titles where Armendáriz appeared with Dolores del Río were Las Abandonadas (1944), Bugambilia (1944) and La Malquerida (1949). Maria Felix was his other partner in such films as Enamorada (1946) or Maclovia (1948).
In the late 40s, he made the jump to Hollywood by the hand of John Ford. Armendáriz was a favorite of Ford, appearing in three of his films: The Fugitive (1947), Fort Apache and 3 Godfathers (both 1948).
Besides his career in the Mexican cinema, Armendáriz made a remarkable career in Hollywood and Europe. His other prominent films in Hollywood were: We Were Strangers (1949, directed by John Huston), The Torch (1950), Border River (1954), The Conqueror (1956) and Diane (1956), among others. In Europe, highlighted his participation in the film Lucrèce Borgia (1953), filmed in France. In Mexico, his participation highlighted such notable films such as El Bruto (1953, directed by Luis Buñuel), La Cucaracha (1959) and La Bandida (1962).
In 1956, Armendáriz had a role in the film The Conqueror produced by Howard Hughes. This movie was filmed in the state of Utah during the time when the US government ran nuclear tests in the neighboring state of Nevada. Ninety-one of the 220 people involved in the production of the film contracted cancer within 25 years, and 46 of these died as a consequence of this illness. In rebuttal, Pilar Wayne (John Wayne's widow) later wrote in her autobiography that she did not believe radiation was involved in the deaths of those associated with this film. She claimed she had visited the set many times as had others and did not become sick. In her opinion, she believed the real cause of death of her husband and the others was solely due to smoking.
Armendáriz began to suffer pain in his hips and years later it was discovered that he had cancer in this region. He learned his condition was terminal while at UCLA Medical Center in Los Angeles, California. He reportedly acted in From Russia with Love while enduring great pain (he visibly limps in most scenes) in order to leave behind financial resources for his family after his impending death. On June 18, 1963, Armendáriz shot himself in the chest with a gun he had smuggled into the hospital. He was buried in Panteón Jardín, Mexico City, Mexico.
