Chalcedonian describes churches and theologians which accept the definition given at the Council of Chalcedon (451 CE) of how the divine and human relate in the person of Jesus Christ.

While most modern Christian churches are Chalcedonian, in the 5th–8th centuries AD the ascendancy of Chalcedonian Christology was not always certain.

The dogmatical disputes raised during this Synod lead to the Chalcedonian schism and as a matter of course to the formation of the non-Chalcedonian body of churches known as Oriental Orthodoxy.

The Chalcedonian churches are the ones that remain united with Rome, Constantinople and the three Roman Orthodox patriarchates of the East (Alexandria, Antioch and Jerusalem), that under Justinian II at the council in Trullo are organized under a form of rule known as the Pentarchy.The majority of the Armenian, Syrian, Coptic, and Ethiopian Christians reject the Chalcedonian definition, and are now known collectively as the Oriental Orthodox churches, but, some Armenian Christians (especially in the region of Cappadocia and Trebizond inside the Byzantine Empire) do accept the decisions of the Council of Chalcedon and engage in polemics against the Armenian Apostolic Church.Churches of the Syriac tradition among the Eastern Catholic Churches are also Chalcedonian.