The Cathedral of Ani (Armenian: Անիի մայր տաճար, Anii mayr tačar; Turkish: Ani Katedrali) is the largest standing building in Ani, the capital city of medieval Bagratid Armenia, located in present-day eastern Turkey, on the border with modern Armenia. Its construction was completed in the early 11th century by the architect Trdat and it was the seat of the Catholicos, the head of the Armenian Apostolic Church, for nearly half a century.

In 1064, following the Seljuk conquest of Ani, the cathedral was converted into a mosque. It later returned to being used as an Armenian church. It eventually suffered damage in a 1319 earthquake when its conical dome collapsed. Subsequently, Ani was gradually abandoned and the church fell into disrepair. The north-western corner of the church was heavily damaged by a 1988 earthquake.

The cathedral is considered the largest and most impressive structure in Ani. It is a domed basilica with a rectangular plan, though the dome and most of its supporting drum are now missing. Its use of pointed arches and cluster piers has been widely cited by scholars to have possibly influenced, or at least preceded, Gothic architecture. The cathedral, along with the entire site of Ani, was declared a World Heritage Site by the UNESCO in 2016.