The Bulgarian St Stephen Church, also known as the Bulgarian Iron Church, is a Bulgarian Orthodox church in Istanbul, famous for being made of cast iron.

The altar of the church faces the Golden Horn and a 40 m-high belfry, the six bells of which were cast in Yaroslavl, rises above the narthex. The church belongs to the Bulgarian minority in the city. The Bulgarians of the Ottoman Empire used to pray at the churches of the Phanar Orthodox Patriarchy, but due to nationalistic movements, Bulgarians were allowed a national church in the 19th century, the Bulgarian Exarchate.

In addition to the St Stephen Church, there is another Bulgarian Orthodox church in Istanbul — the St Demetrius Church in Ferikoy.