Born in Sienno, he was the son of Dobisław z Oleśnicy and Catherine Oleśnicka, daughter of Dmitry of Goraj.

He had ten brothers and sisters, among them Jacob, who was Bishop of Kraków and then Archbishop of Gniezno and Primate of Poland.

He was Przemysl Chamberlain, Starost of Sandomierz, Castellan of Lwów, and Voivode of Ruthenia.

John or Jan distinguished himself fighting under Władysław II Jagiełło against the Grand Master of the Teutonic Order, Świdrygiełłą and he received Świdrygielles Castle as a reward.

He was also the founder of the town Zolochiv(originally "Złoczów", meaning Golden) in 1442 which is now in Ukraine.