Участието на българите като участници в този кръстоносен поход е дибре документирано . Със сигурност това са българите от западните региони и тези
от земите под унгарската корона. Текстът е на английски :On November 9, over 20,000 crusaders reached Varna, outside of which on the next day, they were overwhelmed by about 60,000 Turks and over half of the united army perished.

Late on November 9, a large Ottoman army approached Varna (still held by the Byzantines) from the west. At a supreme military council called by Hunyadi during the night, the Papal legate, cardinal Julian Cesarini, insisted on a quick withdrawal. However, the Christians were closed between the Black sea, Lake Varna, the steep wooded slopes of the Frangen plateau (350 m high), and the enemy. Cesarini then proposed defense using the Wagenburg of the Hussites until the arrival of the Christian fleet. The Hungarian magnates and the Croatian, Bosnian, and Czech commanders backed him, but the young (20-year-old) Władysław and Hunyadi rejected the defensive tactics. Hunyadi declared: "To escape is impossible, to surrender is unthinkable. Let us fight with bravery and honor our arms." Władysław accepted his position and gave him the command.

In the morning of November 10, Hunyadi deployed the army as an arc between Lake Varna and the Frangen plateau; the line was about 3.5 km long. Two banners with a total of 3,500 men from the king's Polish and Hungarian bodyguards, Hungarian royal mercenaries, and banners of Hungarian nobles held the center. The Wallachian cavalry was left in reserve behind the center.

The right flank that lined up the hill towards the village of Kamenar numbered 6,500 men in 5 banners. Bishop Jan Dominek of Varadin with his personal banner led the force; Cesarini commanded a banner of German mercenaries and a Bosnian one. The bishop of Eger lead his own banner, and the military governor of Slavonia, ban Franco Talotsi, commanded one Croatian banner.

The left flank, a total of 5,000 men in 5 banners, was lead by Michael Szilagyi, Hunyadi's brother in law, and was made up of Hunyadi's Transylvanians, Bulgarians, German mercenaries and banners of Hungarian magnates. Behind the Hungarians, closer to the Black Sea and the lake, was the Wagenburg, defended by 300 or 600 Czech and Ruthenian (Ukrainian) mercenaries under hetman Ceyka. Every wagon was manned by 7 to 10 soldiers and the Wagenburg was equipped with bombards.

The Ottoman center included the Janissaries and levies from Rumelia deployed around two Thracian burial mounds. Murad observed and directed the battle from one of them. The Janissaries dug in behind ditches and two palisades. The right wing consisted of Kapikulus and Sipahis from Rumelia, and the left wing was made up by Akıncıs, Sipahis from Anatolia, Arab mercenaries, and other forces. Janissary archers and Akıncı light cavalry were deployed in the Frangen plateau.

The light Ottoman and Arab cavalry assaulted the Croats of ban Talotsi. Christians from the left riposted with bombards and firearms and stopped the attack. Christian soldiers chased the Ottomans and Arabs in a disorderly pursuit. The Anatolian cavalry and Arabs on camels ambushed them from the flank. The Christian right wing attempted to flee to the small fortress of Galata on the other side of Varna Bay, but most of them were slain in the marshland around Varna Lake and the river Devnya, where Cesarini also perished. Only ban Talotsi's troops managed to withdraw behind the Wagenburg.

Władysław and Hunyadi deployed two cavalry companies from the center and the Wallachian cavalry against the Arabs and Anatolian Sipahis, who were routed and their commander, the Anatolian beylerbey Karaca Bey, killed. The Christians pursued them for more than 5-6 km and then returned to the battlefield. The Wallachian cavalry continued the chase and broke into the fortified Ottoman camp. After pillaging and looting, the Wallachians overcharged with gold and other booty left the battlefield.

The other Ottoman flank assaulted the Hungarians and Bulgarians of Michael Szilagyi. Their push was stopped and turned back; then Sipahis attacked again. Hunyadi decided to help and advised the king to wait until he returned; then advanced with two cavalry companies against the Sipahis, defeated and pursued them toward the road to Shumen for 5-6 km. The Sipahis were so terrified that some of them reached and crossed the river Kamchiya some 30 km away.

The European army seemed close to victory; the sultan decided to leave the battlefield. According to Edward Gibbon (The Decline and Fall of the Roman Empire), "When Amurath beheld the flight of his squadrons, he despaired of his fortune and that of the empire: a veteran Janissary seized his horse's bridle; and he had magnanimity to pardon and reward the soldier who dared to perceive the terror, and arrest the flight, of his sovereign."

The young king, ignoring Hunyadi's advice, rushed 500 of his Polish knights against the Ottoman center. They overran the Janissary infantry and the king attempted to take Murad prisoner. Surrounded by Janissary bodyguards, he was slain, his head cut off and later taken to the Ottoman court. The disheartened Polish cavalry was smashed by the Ottomans.

On his return, Hunyadi tried frantically to salvage the king's body but all he could accomplish was to organize the retreat of the remains of his army. It suffered 11,000 (or 13,000) casualties. The Ottomans lost 8,000 (or 20,000) soldiers. They were so shattered by the smaller Christian army that they were unable to pursue them and continue to Central Europe. Many European prisoners were slaughtered or sold as slaves; the minnesinger Michael Beheim wrote a song based on the story of one Hans Mergest who spent 16 years in Ottoman captivity after the battle.