In the year 1380 he was made Grand Duke of Bosnia by Bosnian King Stjepan (Stephen) Tvrtko I of House of Kotromanić, granting him a seat in Lašva. In 1387 Hrvoje's first action as Grand Duke was leading a squadron of Bosnian troops to Croatia to raise the siege of Bishop Ivan Horvat in Zagreb. After the death of king Louis I he participated in the battles of succession between Sigismund of Luxembourg and Ladislaus of Naples. He sided with Ladislaus with the promise of becoming ban of Croatia and Dalmatia in 1391. During the reign of King Stephen Dabiša of Bosnia, he participated in the fights against the Ottoman Turks in Bosnia in 1392 - earning Dabiša's eternal gratitude. Hrvoje became Dabiša's main guarantee of staying at the throne - as he declared that he is a faithful servant of the Hungarian King in all cases but those that might damage King Dabiša in 1393. In the heat of internal struggles in Bosnia in 1397 during the reign of Queen Jelena Gruba Hrvoje invited the Ottomans to offer assistance. As an opposer of Queen Jelena, he participated in the selection of Stephen Ostoja as the new King of Bosnia in May 1398. Opposing King Sigismund's Hungarian pretensions, Hrvoje greatly influenced King Ostoja.