In late 1437, the Estates elected Albert V of Austria as King of Hungary. He died of dysentery during an unsuccessful military operation against the Ottoman Empire in 1439. Although Albert's widow, Elizabeth of Luxembourg, gave birth to a posthumous son, Ladislaus V, most noblemen preferred a monarch capable to fight. They offered the crown to Władysław III of Poland. Both Ladislaus and Władysław were crowned which caused a civil war. John Hunyadi was a leading Hungarian military and political figure in Central and Southeastern Europe during the 15th century.

Władysław appointed Hunyadi (together with his close friend, Nicholas Újlaki) to command the southern defenses in 1441. Hunyadi made several raids against the Ottomans. During his "long campaign" of 1443-1444, the Hungarian forces penetrated as far as Sofia within the Ottoman Empire. The Holy See organized a new crusade, but the Ottomans annihilated the Christian forces at the Battle of Varna in 1444, during which Władysław was killed.

Assembled noblemen elected John Hunyadi's son, Matthias Hunyadi, king in 1458. King Matthias introduced far-reaching fiscal and military reforms. Increased royal revenues enabled Matthias to set up and maintain a standing army. Consisting of mainly Czech, German and Hungarian mercenaries, his "Black Army" was one of the first professional military forces in Europe.^[63] Matthias strengthened the network of fortresses along the southern frontier,^[64] but he did not pursue his father's offensive anti-Ottoman policy. Instead, he launched attacks on Bohemia, Poland, and Austria, arguing that he was trying to forge an alliance strong enough to expel the Ottomans from Europe.

Matthias's court was "unquestionably among the most brilliant in Europe".^[65] His library, the Bibliotheca Corviniana with its 2,000 manuscripts, was the second greatest in size among contemporary book-collections. Matthias was the first monarch north of the Alps to introduce Italian Renaissance style in his realms. Inspired by his second wife, Beatrice of Naples, he had the royal palaces at Buda and Visegrád rebuilt under the auspices of Italian architects and artists after 1479.