The Patriarchate of Karlovci or Serbian Patriarchate of Sremski Karlovci, was a patriarchate of the Eastern Orthodox Church that existed between 1848 and 1920. It was formed when the Metropolitanate of Karlovci was elevated to the rank of patriarchate. The Patriarchate of Karlovci nominally existed until 1920, when along with several other Eastern Orthodox jurisdictions in the defunct Austro-Hungarian Empire, as well as the Metropolitanate of Cetinje, it was merged with the Metropolitanate of Belgrade to form the united Serbian Orthodox Church. The seat of the Patriarchate was in Karlovci.

The Metropolitanate of Karlovci was a metropolitanate of the Eastern Orthodox Church that existed in the Habsburg monarchy between 1708 and 1848. Between 1708 and 1713, it was known as the Metropolitanate of Krušedol, and between 1713 and 1848, as the Metropolitanate of Karlovci. In 1848, it was elevated to the Patriarchate of Karlovci, which existed until 1920, when it was merged with the Metropolitanate of Belgrade and other Eastern Orthodox jurisdictions in the newly established Kingdom of Serbs, Croats and Slovenes to form the Serbian Orthodox Church.