Following the end of the First World War (1914-1918), the Kingdom of Montenegro was united with the Kingdom of Serbia on 26 (13 o.s.)
November 1918, by the proclamation of the newly elected Podgorica Assembly, and soon after that, on 1 December of the same year, the Kingdom of Serbs, Croats and Slovenes was created, known since 1929 as the Kingdom of Yugoslavia.
The political and national unification was carried out under the auspices of the Karađorđević dynasty, and thus a long-standing dynastic rivalry between the two royal families, the Petrović-Njegoš dynasty of Montenegro and the Karađorđević dynasty of Serbia, was finally resolved, without mutual agreement.

Political unification was followed by the unification of all Eastern Orthodox jurisdictions within the borders of the new state.
 Initial decision to include dioceses in Montenegro into the process of ecclesiastical unification was reached on 29 (16 o.s.)
December 1918 by the Holy Synod, consisted of all three hierarchs in Montenegro: Mitrofan Ban of Cetinje, Kirilo Mitrović of Nikšić, and Gavrilo Dožić of Peć.
On that day, the Holy Synod met in Cetinje and unanimously accepted the following proposal: "The independent Serbian Orthodox Holy Church in Montenegro shall be united with the autocephalous Orthodox Church in the Kingdom of Serbia".
Soon after that, further steps towards ecclesiastical unification were made.
From 24 to 28 May 1919, a conference of all Eastern Orthodox bishops within the borders of the unified state was held in Belgrade, and it was presided by metropolitan Mitrofan Ban of Montenegro, who was also elected president of the newly created Central Synod.
Under his leadership, the Central Synod prepared the final proclamation of Church unification on 12 September 1920.
The creation of the unified Serbian Orthodox Church was also confirmed by King Alexander I.
Old metropolitan Mitrofan Ban was succeeded in the autumn of 1920 by Gavrilo Dožić, who became new Metropolitan of Montenegro and the Littoral.
In 1931, under the provisions of the newly adopted Constitution of the Serbian Orthodox Church, the Eparchy of Zahumlje and Raška with its seat in Nikšić was abolished, and its territory was added to the Metropolitanate of Montenegro and the Littoral.
In the same time, the Eparchy of Kotor and Dubrovnik was also abolished, and divided, its Kotor region being added to the Metropolitanate.
In 1938, Metropolitan Gavrilo Dožić of Montenegro was elected Serbian Patriarch, and Joanikije Lipovac was elected new Metropolitan of Montenegro and the Littoral, in 1940.

During the Second World War, Yugoslavia was occupied by Axis powers in 1941, and the territory of Montenegro was organized as the Italian governorate of Montenegro (1941-1943), followed by the German occupation of Montenegro (1943-1944).
The Metropolitanate was affected severely during the occupation, and more than hundred priests and other clergymen from the territory of Montenegro lost their lives during the war.
During that time, Montenegrin fascist Sekula Drljević tried to create an independent Kingdom of Montenegro, as a satellite state of Fascist Italy and Nazi Germany, but that project failed because of the lack of support among people.
His attempt was challenged by the 13 July Uprising in 1941, which had support from the both sides of political spectrum.
Metropolitan Joanikije Lipovac cooperated closely with several right-wing movements, and also tried to mediate with local Italian and German officials in occupied Montenegro, thus provoking animosity of the left-wing Yugoslav Partisans.
In 1944, when Yugoslav Communists took the power, he had to flee, but was arrested and executed without trial in 1945.
In 2001, he was sanctified as a hieromartyr by the Serbian Orthodox church.

Under the Yugoslav Communist rule (1944-1989), the Metropolitanate suffered constant repression at the hands of the new regime.
Persecution was particularly severe during the first years of Communist rule (1944-1948) The new regime exerted direct pressure on the clergy in order to crush all forms of anti-communist
Following the end of the First World War (1914-1918), the Kingdom of Montenegro was united with the Kingdom of Serbia on 26 (13 o.s.) November 1918, by the proclamation of the newly elected Podgorica Assembly, and soon after that, on 1 December of the same year, the Kingdom of Serbs, Croats and Slovenes was created, known since 1929 as the Kingdom of Yugoslavia. The political and national unification was carried out under the auspices of the Karađorđević dynasty, and thus a long-standing dynastic rivalry between the two royal families, the Petrović-Njegoš dynasty of Montenegro and the Karađorđević dynasty of Serbia, was finally resolved, without mutual agreement.
Political unification was followed by the unification of all Eastern Orthodox jurisdictions within the borders of the new state.  Initial decision to include dioceses in Montenegro into the process of ecclesiastical unification was reached on 29 (16 o.s.) December 1918 by the Holy Synod, consisted of all three hierarchs in Montenegro: Mitrofan Ban of Cetinje, Kirilo Mitrović of Nikšić, and Gavrilo Dožić of Peć. On that day, the Holy Synod met in Cetinje and unanimously accepted the following proposal: "The independent Serbian Orthodox Holy Church in Montenegro shall be united with the autocephalous Orthodox Church in the Kingdom of Serbia". Soon after that, further steps towards ecclesiastical unification were made. From 24 to 28 May 1919, a conference of all Eastern Orthodox bishops within the borders of the unified state was held in Belgrade, and it was presided by metropolitan Mitrofan Ban of Montenegro, who was also elected president of the newly created Central Synod. Under his leadership, the Central Synod prepared the final proclamation of Church unification on 12 September 1920. The creation of the unified Serbian Orthodox Church was also confirmed by King Alexander I.
Old metropolitan Mitrofan Ban was succeeded in the autumn of 1920 by Gavrilo Dožić, who became new Metropolitan of Montenegro and the Littoral. In 1931, under the provisions of the newly adopted Constitution of the Serbian Orthodox Church, the Eparchy of Zahumlje and Raška with its seat in Nikšić was abolished, and its territory was added to the Metropolitanate of Montenegro and the Littoral. In the same time, the Eparchy of Kotor and Dubrovnik was also abolished, and divided, its Kotor region being added to the Metropolitanate. In 1938, Metropolitan Gavrilo Dožić of Montenegro was elected Serbian Patriarch, and Joanikije Lipovac was elected new Metropolitan of Montenegro and the Littoral, in 1940.
During the Second World War, Yugoslavia was occupied by Axis powers in 1941, and the territory of Montenegro was organized as the Italian governorate of Montenegro (1941-1943), followed by the German occupation of Montenegro (1943-1944). The Metropolitanate was affected severely during the occupation, and more than hundred priests and other clergymen from the territory of Montenegro lost their lives during the war. During that time, Montenegrin fascist Sekula Drljević tried to create an independent Kingdom of Montenegro, as a satellite state of Fascist Italy and Nazi Germany, but that project failed because of the lack of support among people. His attempt was challenged by the 13 July Uprising in 1941, which had support from the both sides of political spectrum. Metropolitan Joanikije Lipovac cooperated closely with several right-wing movements, and also tried to mediate with local Italian and German officials in occupied Montenegro, thus provoking animosity of the left-wing Yugoslav Partisans. In 1944, when Yugoslav Communists took the power, he had to flee, but was arrested and executed without trial in 1945. In 2001, he was sanctified as a hieromartyr by the Serbian Orthodox church.
Under the Yugoslav Communist rule (1944-1989), the Metropolitanate suffered constant repression at the hands of the new regime. Persecution was particularly severe during the first years of Communist rule (1944-1948) The new regime exerted direct pressure on the clergy in order to crush all forms of anti-communist
Metropolitanate of Montenegro and the Littoral