The Serbian Orthodox Church (SOC; Serbian: Српска православна црква, СПЦ, Srpska pravoslavna crkva, SPC) is one of the autocephalous (ecclesiastically independent) Eastern Orthodox Christian churches.

The majority of the population in Serbia, Montenegro and Republika Srpska of Bosnia and Herzegovina are baptised members of the Serbian Orthodox Church. It is organized into metropolitanates and eparchies, located primarily in Serbia, Bosnia and Herzegovina, Montenegro, and Croatia. Other congregations are located in the Serb diaspora. The Serbian Patriarch serves as first among equals in his church. The current patriarch is Porfirije, enthroned on 19 February 2021.

The Church achieved autocephalous status in 1219, under the leadership of Saint Sava, becoming the independent Archbishopric of Žiča. Its status was elevated to that of a patriarchate in 1346, and was subsequently known as the Serbian Patriarchate of Peć. This patriarchate was abolished by the Ottoman Empire in 1766, though several regional sections of the church continued to exist, most prominent among them being the Metropolitanate of Karlovci, in the Habsburg monarchy. After the re-creation of Serbia, ecclesiastical autonomy was regained in 1831, and the autocephaly was renewed in 1879. The modern Serbian Orthodox Church was re-established in 1920, after the unification of the Metropolitanate of Belgrade, the Patriarchate of Karlovci, and the Metropolitanate of Montenegro.

Christianity started to spread throughout the southeastern Europe during the 1st century. Early martyrs Florus and Laurus from the 2nd century, who were murdered along with other 300 Christians in Ulpiana, near modern Lipljan, are venerated as Christian saints. Bishop Irenaeus of Sirmium was also martyred, in 304. Emperor Constantine the Great (306–337), born in Naissus (modern Niš in Serbia), was the first Christian ruler of the Roman Empire. Several local bishops, seated in present-day Serbia, became prominent during the 4th century, such as Germinius of Sirmium, Ursacius of Singidunum and Secundianus of Singidunum (modern Belgrade), while several Councils were held in Sirmium.

In 395, the Empire was divided, and its eastern half later became the Eastern (Byzantine) Empire. In 535, emperor Justinian I created the Archbishopric of Justiniana Prima, centered in the emperor's birth-city of Justiniana Prima, near modern Lebane in Serbia. The archbishopric had ecclesiastical jurisdiction over all provinces of the Diocese of Dacia. By the beginning of the 7th century, Byzantine provincial and ecclesiastical order in the region was destroyed by invading Avars and Slavs. The church life was renewed in the same century in the province of Illyricum and Dalmatia after a more pronounced Christianization of the Serbs and other Slavs by the Roman Church. In the 7th and mid-8th century the area was not under jurisdiction of the Patriarchate of Constantinople.

The history of the early medieval Serbian Principality is recorded in the work De Administrando Imperio (DAI), compiled by the Byzantine Emperor Constantine VII Porphyrogenitus (r.  913–959). The DAI drew information on the Serbs from, among others, a Serbian source. The Serbs were said to have received the protection of Emperor Heraclius (r. 610–641), and Porphyrogenitus stressed that the Serbs had always been under Imperial rule. According to DAI, the Serbs at first received their baptism from Rome. His account on the first Christianization of the Serbs can be dated to 632–638; this might have been Porphyrogenitus' construction, or may have encompassed a limited group of chiefs, with lesser reception by the wider layers of the tribe. From the 7th until mid-9th century, the Serbs were under influence of the Roman Church. The initial ecclesiastical affiliation with a specific diocese is uncertain, probably was not an Adriatic centre. Early medieval Serbs are accounted as Christian by 870s, but it was a process that ended in the late 9th century during the time of Basil I, and medieval necropolises until the 13th century in the territory of modern Serbia show an "incomplete process of Christianization" as local Christianity depended on the social structure (urban and rural).

The expansion of the Ecumenical Patriarchate of Constantinople over the Praetorian prefecture of Illyricum is considered to have begun in 731 by Emperor Leo III when he annexed Sicily and Calabria, but whether the Patriarchate also expanded into the eastern parts of Illyricum and Dalmatia is uncertain and a matter of scholarly debate. The expansion most definitely happened since the mid-9th century, when the Byzantines emperors and patriarch demanded that the Church administrative borders follow political borders. In the same century, the region was also politically contested between the Carolingian Empire and Byzantine Empire. The most influential and successful was emperor Basil I, who actively worked on gaining control over all of Illyricum. Basil I likely sent at least one embassy to Mutimir of Serbia, who decided to maintain the communion of Church in Serbia with the Patriarchate of Constantinople when Pope John VIII invited him to return to the jurisdiction of the bishopric of Sirmium (see also Archbishopric of Moravia) in a letter dated to May 873.

Alexis P. Vlasto argued that the Eparchy of Ras was founded during Mutimir's rule, as a bishopric of Serbia, at Ras with the church of Saint Apostles Peter and Paul, as part of the general plan of establishing bishoprics in the Slav lands of the Empire, confirmed by the Council of Constantinople in 879–880, most significantly related to the creation of the autonomous Archbishopric for Bulgaria of which Roman Church lost jurisdiction. However, according to Predrag Komatina, there is no mention of any bishopric in Serbia. In early medieval Europe, the existence of a Christian church without a bishop in a specific land was not uncommon, and being placed under the Pannonian Bishop implies that there was no local Serbian bishop at the time. Tibor Živković concluded, based on primary sources of the Church of Constantinople, that there was no information regarding the establishment of any new ecclesiastical center and organization in Serbia, that the Serbian ecclesiastical center and capital was at Destinikon, while Ras in the mid-9th century was only a border fort which became the ecclesiastical center of the bishopric by 1019-1020. The imperial charter of Basil II from 1020 to the Archbishopric of Ohrid, in which the rights and jurisdictions were established, has the earliest mention of the Bishopric of Ras, stating it belonged to the Bulgarian autocephalous church during the time of Peter I (927–969) and Samuel of Bulgaria (977–1014). It was of a small size. It is considered that it was possibly founded by the Bulgarian emperor, but most probably it represented the latest date in which it could have been integrated into the Bulgarian Church. The Ras bishopric was probably part of the Bulgarian metropolis of Morava, but certainly not of Dyrrhachium. If it was in Serbian territory, it seems that the Church in Serbia or part of the territory of Serbia became linked and influenced by the Bulgarian Church between 870 and 924.