Jankélévitch was the son of Russian Jewish parents, who had emigrated to France. In 1922 he started studying philosophy at the École normale supérieure in Paris, under Professor Bergson. From 1927 to 1932 he taught at the Institut Français in Prague, where he wrote his doctorate on Schelling. He returned to France in 1933, where he taught at the Lycée du Parc in Lyon and at many universities, including Toulouse and Lille. In 1941 he joined the French Resistance. After the war, in 1951, he was appointed to the chair of Moral Philosophy at the Sorbonne, where he taught until 1978.

The extreme subtlety of his thought is apparent throughout his works where the very slightest gradations are assigned great importance. Jankelevitch, who drew on Platonist, Neoplatonist and Greek Patristic sources in establishing his essentially agnostic thought, was resolute in his opposition to German philosophical influence.