The Kingdom of Montenegro was a monarchy in southeastern Europe, present-day Montenegro, during the tumultuous period of time on the Balkan Peninsula leading up to and during World War I. Officially it was a constitutional monarchy, but absolutist in practice. On 28 November 1918, following the end of World War I, with the Montenegrin government still in exile, the Podgorica Assembly proclaimed unification with the Kingdom of Serbia, which itself was merged into the Kingdom of Serbs, Croats and Slovenes three days later, on 1 December 1918. This unification with Serbia lasted, through various successor states, for almost 88 years, ending in 2006.

Montenegro is a country in Southeast Europe, located in the Balkans. It is bordered by Bosnia and Herzegovina to the north, Serbia to the northeast, Kosovo to the east, Albania to the southeast, and Croatia and the Adriatic Sea to the northwest with a coastline of 293.5 km. Podgorica is the country's capital and its largest city; it covers 10.4% of Montenegro's territory of 13,812 square kilometres (5,333 sq mi), and is home to roughly 31% of its total population of 621,000. Cetinje is the former royal capital and cultural centre of Montenegro and is the location of several national institutions, including the official residence of the President of Montenegro.