The subject of this paper is the Kingdom of Hungary in the 14th and 15th century, focusing on one of the most powerful rulers of the time – King Matthias Corvinus, remembered by the people as a righteous ruler. In order to understand why he was chosen and crowned king as a member of lower aristocracy, the paper discusses the complex political and economic relations that preceded his being chosen and crowned king – from the time of the rule of the kings of the House of Anjou (Charles I Robert and Louis I), Sigismund of Luxembourg, Albert II of Habsburg to Vladislav I Jagelovský, and their attempts to modernize the kingdom by implementing administrative, economic and military reforms.The paper presents the rule of King Matthias Corvinus with an emphasis on the activities and decisions that enabled him to remove the self-rule of magnates and to establish a centralist monarchy, on implementing administrative, financial, judicial and military reforms and establishing a line of defence to protect the southern boundaries of the Kingdom from the Ottoman attacks, as well as wars with the Czech Republic and Austria, and on his contribution to the development of Humanism and Renaissance at the Hungarian court.