He was the only surviving son of Henry III and his wife Beatrix of Lower Bavaria, the daughter of Duke Stephen I.

Because he was still a minor, his mother and his uncles Albert II of Gorizia and later Henry of Carinthia acted as regents.

Nevertheless, in 1332, aged nine, he was elected as podesta of Trieste, in the city's attempt to forge an alliance with Gorizia against Venetian expansion.

[3] In 1335, with a treaty signed in Ljubljana, John Henry thus betrothed to Anna of Habsburg, the daughter of the anti-king Frederick the Fair, who was a second cousin in his mother.

[citation needed] Since he died childless, he was succeeded by the sons of his uncle Albert II.