The Treaty of Berlin (formally the Treaty between Austria-Hungary, France, Germany, Great Britain and Ireland, Italy, Russia, and the Ottoman Empire for the Settlement of Affairs in the East) was signed on 13 July 1878. In the aftermath of the Russian victory against the Ottoman Empire in the Russo-Turkish War of 1877–1878, the major powers restructured the map of the Balkan region. They reversed some of the extreme gains claimed by Russia in the preliminary Treaty of San Stefano, but the Ottomans lost their major holdings in Europe. It was one of three major peace agreements in the period after the 1815 Congress of Vienna. It was the final act of the Congress of Berlin (13 June – 13 July 1878) and included Great Britain and Ireland, Austria-Hungary, France, Germany, Italy, Russia and the Ottoman Empire. Chancellor of Germany Otto von Bismarck was the chairman and dominant personality.

The most important task of the Congress was to decide the fate of Bulgaria, but Bulgaria itself was excluded from participation in the talks, at Russian insistence. At the time, as it was not a sovereign state, Bulgaria was not a subject of international law, and the same went for the Bulgarians themselves. The exclusion was already an established fact in the great powers' Constantinople Conference, which had been held one year before without any Bulgarian participation.

The most notable result of the conference was the official recognition of (which had de facto been acting independently for decades) the newly independent states of Romania, Serbia and Montenegro.