Okada served in the Imperial Japanese Army during World War II and was a miner and traveling salesman before becoming an actor.

[1] Internationally, his best-remembered roles include Lui ("him" in French) in the 1959 film Hiroshima mon amour, directed by Alain Resnais.

In this film, Eiji Okada had to learn the screenplay phonetically because he did not speak French.

He is also known for playing the entomologist Niki Junpei in Hiroshi Teshigahara's 1964 film Woman in the Dunes, an adaptation of Kōbō Abe's novel.

Okada was married to Aiko Wasa, with whom he ran a theatre company in Japan.