The Battle of Sisak was fought on 22 June 1593 between Ottoman Bosnian forces and a combined Christian army from the Habsburg lands, mainly Kingdom of Croatia and Inner Austria. The battle took place at Sisak, central Croatia, at the confluence of the Sava and Kupa rivers, on the borderland between Christian Europe and the Ottoman Empire.

Between 1591 and 1593 the Ottoman military governor of Bosnia, Beglerbeg Telli Hasan Pasha, attempted twice to capture the fortress of Sisak, one of the garrisoned castles that the Habsburgs maintained in Croatia as part of the Military Frontier. In 1592 after the key imperial fortress of Bihać fell to the Turks, only Sisak stood in the way before Croatia's main city Zagreb. Pope Clement VIII called for a Christian league against the Ottomans and the Sabor recruited in anticipation a force of about 5,000 professional soldiers.

On 15 June 1593, Sisak was once again besieged by the Bosnian Pasha and his Ghazi warriors. The Sisak garrison was commanded by Blaž Đurak and Matija Fintić, both Croatians from the Diocese of Zagreb. A Habsburg relief army under the supreme command of the Styrian general Ruprecht von Eggenberg, was quickly assembled to break the siege. The Croatian troops were led by the Ban of Croatia, Tamás Erdődy, while major forces from the Duchy of Carniola and the Duchy of Carinthia were under the commander of the Croatian Military Frontier Andreas von Auersperg, known as the "Carniolan Achilles".

On 22 June the Austro-Croatian relief army launched a surprise attack on the besieging forces, at the same time the garrison came out of the fortress to join the attack, the ensuing battle resulted in a crushing defeat for the Bosnian Ottoman army with Hasan Pacha killed and nearly all his army wiped out.

The battle of Sisak is considered the main catalyst for the start of the Long War which raged between the Habsburgs and the Ottomans from 1593 to 1606.