Milan was a novelist. He went into exile in France in 1975, acquiring citizenship in 1981. His Czech citizenship was revoked in 1979, but he was regranted citizenship in 2019. Milan's best-known work is "The Unbearable Lightness of Being". Before the Velvet Revolution of 1989, the country's ruling Communist Party of Czechoslovakia banned his books. He led a low-profile life and rarely spoke to the media. He was thought to be a contender for the Nobel Prize in Literature. Milan was awarded the 1985 Jerusalem Prize, in 1987 the Austrian State Prize for European Literature, and the 2000 Herder Prize. In 2021, he received the Golden Order of Merit from the president of Slovenia, Borut Pahor.
Milan was an atheist and seemed to have a naturalistic worldview, having said "I was never a believer, but after seeing Czech Catholics persecuted during the Stalinist terror, I felt the deepest solidarity with them. What separated us, the belief in God, was secondary to what united us." He seemed to have a sentiocentric moral scope, saying "Humanity's true moral test, its fundamental test... consists of its attitude towards those who are at its mercy: animals. And in this respect humankind has suffered a fundamental debacle, a debacle so fundamental that all others stem from it." He also said "What seems more likely, in fact, is that man invented God to sanctify the dominion that he had usurped for himself over the cow and the horse."