Vadim was born as Roger Vladimir Plemiannikov in Paris. His Russian father, Igor Nikolaevich Plemiannikov, had immigrated from Ukraine and became a naturalized French citizen, and was a vice consul of France to Egypt. Vadim became a stage actor at the age of 16. In 1947 he became assistant writer to film director Marc Allégret.
Vadim was celebrated for his romances/marriages to beautiful actresses. He wrote about these in his 1986 book Bardot, Deneuve & Fonda.