He is known for the discovery of the Faddeev equations in the quantum-mechanical three-body problem and for the development of path-integral methods in the quantization of non-abelian gauge field theories, including the introduction of the Faddeev–Popov ghosts (with Victor Popov).

His father, Dmitry Faddeev, was a well-known algebraist, professor of Leningrad University and member of the Russian Academy of Sciences.

[2] From 1976 to 2000, Faddeev was head of the St. Petersburg Department of Steklov Institute of Mathematics of Russian Academy of Sciences (PDMI RAS).

[4] In 1988 he founded the Euler International Mathematical Institute, now a department of PDMI RAS.

[11] Also the Karpinsky International Prize and the Max Planck Medal (German Physical Society).