János Ferencsik (18 October 1907 – 12 June 1984) was a Hungarian conductor.
Ferencsik was born in Budapest; he actively played music even as a very young boy. He took violin lessons and taught himself to play the organ. He studied at the National Conservatory of Music in Budapest, where his major subjects were organ performance and composition. He joined the Budapest State Opera at the age of twenty, where he was engaged as a rehearsal coach. In this capacity he took part in the Bayreuth Festival in 1930 and 1931. In Bayreuth, he assisted Arturo Toscanini, an experience which was to be of decisive importance for the remainder of his career.
Ferencsik's international career began in 1937. By the end of the 1930s, he was one of the Hungarian Opera's leading conductors. His artistic career came to fuil fruition after 1945. He was appointed General Music Director of the Budapest Opera, Principal Conductor of the Hungarian National Philharmonic Orchestra in Budapest and, from 1960 until 1967, Conductor Chairman of the Budapest Philharmonic Orchestra. From 1948 until 1950, Ferencsik was principal guest conductor of the Vienna State Opera. He toured widely abroad, conducting on every continent with the exception of Africa.