Orthodoxy in the United Kingdom (Great Britain and Northern Ireland) consists of several jurisdictions which have churches and dioceses which are located in, or cover the territory of, the United Kingdom.
The majority of Orthodox in the United Kingdom belong to the Ecumenical Patriarchate's Archdiocese of Thyateira and Great Britain, which is based in London and which has had a presence in Britain since the 17th Century. The archdiocese includes a number of parishes which have historically been of Slavic tradition, derived in large part from post-World War II arrivals from Poland.
The churches of the Serbian Orthodox Diocese of Great Britain and Scandinavia located in the United Kingdom constitute the second largest Orthodox jurisdiction in the British Isles.
The Diocese of Sourozh is the diocese of the Moscow Patriarchate to which most of its Churches and communities belong. Other Russian Churches are either stavropegic or belong to the Western European Diocese of the Russian Orthodox Church Outside Russia.
In 2006, a number of churches and members of the Diocese of Sourozh left the jurisdiction of the Moscow Patriarchate and were received into the Patriarchal Exarchate for Orthodox Parishes of Russian Tradition in Western Europe, under the jurisdiction of the Ecumenical Patriarch and based in Paris. They now constitute the Episcopal Vicariate in Great Britain and Ireland.
The Church of Antioch has a cathedral in London and the Antiochian Orthodox Deanery of the United Kingdom and Ireland, whose churches and communities are located in various parts of England and Ireland.
The Ukrainian Orthodox Diocese in Western Europe, under the jurisdiction of the Ecumenical Patriarchate, also has a presence in the United Kingdom, as do the Church of Romania and the Church of Bulgaria.