St. Clement's Cathedral, Prague, Catholic cathedral in Old Town, Czech Republic

St. Clement's Cathedral is a single-nave Baroque church built for the Jesuits in the Clementinum between 1711 and 1715. Its exterior is modest, with a tall prismatic tower topped by a Baroque onion dome. Inside, the vault bears four frescoes of Saint Clement's life painted by Jan Hiebel in 1714–1715.

The building was constructed between 1711 and 1715, replacing a Gothic church that Hussite forces destroyed in 1420. This Baroque reconstruction marked religious restoration in the district following centuries of earlier destruction.

The church serves the Ruthenian Catholic Apostolic Exarchate of the Czech Republic, erected by Pope John Paul II's bull of 13 March 1996. Since the early 21st century it has drawn mainly Ukrainian Greek Catholics, and after 2022 became a main centre of Ukrainian religious life in Czechia. The iconostasis was replaced in 1984 with a design by Karel Stádník.

The cathedral stands in the Clementinum complex in Prague's Old Town, near the Charles Bridge; the entrance faces the square. The passage that once linked it to the Church of the Holy Saviour through a shared sacristy is now closed. It serves as the cathedral of the Ruthenian Catholic Apostolic Exarchate and is a place of worship, so visits should respect services.

In the crypt below the church are walled burial niches (loculi); among those buried there is the chronicler Václav Hájek z Libočan, who died in 1553 in the nearby Dominican convent of St. Anne. The church also served as the model for the church of St. Francis Xavier at the Jesuit monastery in Opařany.