The collapse of the Central Powers came swiftly. Bulgaria was the first to sign an armistice on 29 September 1918 at Saloniki. On 30 October the Ottoman Empire capitulated at Mudros.

On 24 October the Italians began a push which rapidly recovered territory lost after the Battle of Caporetto. This culminated in the Battle of Vittorio Veneto, which marked the end of the Austro-Hungarian Army as an effective fighting force. The offensive also triggered the disintegration of Austro-Hungarian Empire. During the last week of October declarations of independence were made in Budapest, Prague and Zagreb. On 29 October, the imperial authorities asked Italy for an armistice. But the Italians continued advancing, reaching Trento, Udine and Trieste. On 3 November Austria–Hungary sent a flag of truce to ask for an Armistice. The terms, arranged by telegraph with the Allied Authorities in Paris, were communicated to the Austrian Commander and accepted. The Armistice with Austria was signed in the Villa Giusti, near Padua, on 3 November. Austria and Hungary signed separate armistices following the overthrow of the Habsburg monarchy.

Following the outbreak of the German Revolution, a republic was proclaimed on 9 November. The Kaiser fled to the Netherlands. On 11 November an armistice with Germany was signed in a railroad carriage at Compi├Ęgne. At 11 a.m. on 11 November 1918; "the eleventh hour of the eleventh day of the eleventh month"; a ceasefire came into effect. Opposing armies on the Western Front began to withdraw from their positions. Canadian Private George Lawrence Price is traditionally regarded as the last soldier killed in the Great War: he was shot by a German sniper at 10:57 and died at 10:58.

Allied superiority and the stab-in-the-back legend, November 1918

In November 1918 the Allies had ample supplies of men and materiel to invade Germany, yet at the time of the armistice, no Allied soldier had set foot on German soil in anger and Berlin was still almost 900 mi (1,400 km) from the Western Front. The Kaiser's armies had also retreated from the battlefield in good order which enabled Hindenburg and other senior German leaders to spread the story that their armies had not really been defeated. This resulted in the stab-in-the-back legend which attributed Germany's losing the war not to its inability to continue fighting (even though up to a million soldiers were suffering from the Spanish Flu and unfit to fight), but to the public's failure to respond to its "patriotic calling" and the intentional sabotaging of the war effort, particularly by Jews, Socialists and Bolsheviks.

A formal state of war between the two sides persisted for another seven months, until signing of the Treaty of Versailles with Germany on 28 June 1919. Later treaties with Austria, Hungary, Bulgaria and the Ottoman Empire were signed. However, the latter treaty with the Ottoman Empire was followed by strife (the Turkish Independence War) and a final peace treaty was signed between the Allied Powers and the country that would shortly become the Republic of Turkey, at Lausanne on 24 July 1923.

Some war memorials date the end of the war as being when the Versailles treaty was signed in 1919; by contrast, most commemorations of the war's end concentrate on the armistice of 11 November 1918. Legally the last formal peace treaties were not signed until the Treaty of Lausanne. Under its terms, the Allied forces divested Constantinople on 23 August 1923.