Béla is the only son of Duke Álmos, the younger brother of King Coloman of Hungary; his mother was Predslava of Kiev.

Duke Álmos had led several rebellions against his brother, but finally, he and Béla were blinded in 1113.

Father and son were living together in the Premonstratensian Monastery of Dömös until 1126, when Duke Álmos tried to organize a conspiracy against King Stephen II, King Coloman's son and heir.

Stephen had given shelter to the Pechenegs (besenyő), who had been defeated totally by the Emperor John II Komnenos, and organized them in a troop of bodyguards, which had resulted in the conspiracy aimed at the restoration of Duke Álmos.

However, the conspiracy had been revealed and Duke Álmos had been obliged to escape to the protection of Constantinople.

Following his father's escape, Béla is taken secretly to the Monastery of Pécsvárad by his father's partisans.

Stephen has a meeting with Duke Sobeslav I of Bohemia in the autumn of 1126 and they make peace.