He was the chaplain of the Knights of Street John. He was also the last representative of the Medieval Inquisition in Malta. In 1541 he was appointed and consecrated bishop of Malta.
He received his episcopal ordination in Sicily.
He built his Episcopal Palace in Birgu which later became the Inquisitor"s Palace. On October 21, 1561 Pope Pius IV established the Roman Inquisition in Malta and Cubelles was appointed as the first Inquisitor of Malta by the bull "Licet ab Initio" on 15 July 1562.
Cubelles also served as bishop during the Great Siege of Malta of 1565. Bishop Cubelles dies on November 22, 1566.
