Of Polish-Jewish descent, Illich-Svitych was born in Kiev but in 1941 moved with his parents to Chkalov and later to Moscow. His father, Mark Vladislavovich Illich-Svitych (1886—1963), worked as a bookkeeper; mother, Klara Moiseevna Desner (1901—1955) was chief director of puppet theater in Orenburg.
He resuscitated the long-forgotten Nostratic hypothesis, originally expounded by Holger Pedersen in 1903, and coined the modern term Nostratics. His death prevented him from completing the Comparative Dictionary of Nostratic Languages, but the ambitious work was continued by his colleagues, including Sergei Starostin and Vladimir Dybo.
He died in an automobile accident on August 22, 1966, near Moscow.