Born in Prague, John was the third son of Emperor Charles IV (1316–1378) from his fourth marriage with the Griffin princess Elizabeth (c. 1347–1393), daughter of Duke Bogislaw V of Pomerania.

In 1377, one year before his death, Emperor Charles IV provided for his younger son the bailiwick of Görlitz in the Bohemian crown land of Upper Lusatia, which he raised to a duchy in its own right.

In 1385 King Wenceslaus consigned him administration of Brandenburg, then formally under the rule of John's half-brother Sigismund and given in pawn to their cousin Margrave Jobst of Moravia three years later.

When during the struggles with his cousin Jobst of Moravia in 1394, Wenceslaus was arrested and kept prisoner (8 May - 1 August) in Austria, he was only set free after John occupied Prague, raised an army at Kutná Hora (Kuttenberg), and campaigned the lands of the insurgent Rosenberg family to intervene for his brother.

On 10 February 1388 in Prague, John married Richardis Catherine (d. 1400), a daughter of Duke Albert III of Mecklenburg, who ruled as King of Sweden from 1364 to 1389.