St Martin's Cathedral (Slovak: Katedrála svätého Martina, Hungarian: Szent Márton-dóm or Koronázó templom, German: Kathedrale des Heiligen Martin) is a church in Bratislava, Slovakia, and the cathedral of the Archdiocese of Bratislava.

It is situated at the western border of the historical city center below Bratislava Castle. It is the largest and one of the oldest churches in Bratislava, known especially for being the coronation church of the Kingdom of Hungary between 1563 and 1830.

Together with the castle on the hill adjacent, and somewhat similar in its striking, but fairly stark Gothic lines and colouring, St Martin's tower and spire, at 85 metres (278 ft 10 in), dominates Old Town's skyline. The tower virtually formed a part of the town's fortifications, built as it was into the city's defensive walls.

As with the castle, the surroundings of St Martin's are as memorable as the structure itself. In the cathedral's case, this includes the picturesque remains of outbuildings in a spacious staired courtyard, and a working seminary with robed students on a cobblestone side-street.

A small but significant neighbour of the cathedral is a monument to the synagogue, which stood next door for centuries until the Communist government demolished it around 1970 to make room for a new bridge, Nový Most. The cathedral contains the remains of Saint John the Merciful who died in the early 7th century.