Vitéz was born in Sredna near Križevci in a Croat-Hungarian family which was already influential at the Hungarian court. Vitéz's mother was originated from the Garázda genus (originally from Bosnia, genus is named after Goražde). On his father's side he derived from Pilis county (his father's surname was originally Csévi). His father was the secretary of the regent John Hunyadi, from 1446 to 1452. Vitéz became a prothonotary in his government.
Vitéz studied in Vienna, where he graduated in law and became knowledgeable in physics, astronomy and alchemy due to frequent contacts with other humanists. In the chancery of King Sigismund, he probably met the excellent Italian humanist Pier Paolo Vergerio. For a while (around 1437) he was the canon in Zagreb. In that period, he helped strengthen the relations between the Croatian capital and the thriving Italian cultural and scientific centers. Then he left for Hungary, where he was to play a major role in the development of cultural and scientific institutions.