Llandaff Cathedral is situated in the suburb of Llandaff in the city of Cardiff, the capital of Wales, and is the seat of the Bishop of Llandaff. The cathedral is dedicated to Saint Peter and Saint Paul, and also to three Welsh saints: Dyfrig, Teilo, and Euddogwy. There is evidence for Christian worship on the site from the 6th century, and a church was built by Teilo on the bank of the River Taff. After his death, his shrine became a place of pilgrimage. The monastic settlement survived for many centuries before the establishment of the diocese of Llandaff following the Norman Conquest.

The Normans occupied Glamorgan early, and appointed the first bishop in 1108. He began construction of the cathedral in 1120, but it was not completed until 1290. The west front dates from 1220, and contains a statue of Teilo. The Lady Chapel was built by William de Braose, who was bishop from 1266 to 1287. Damage to the church was done during the revolt of Owen Glendower in 1400, and the bishop's palace was destroyed. However, most of the other damage was repaired,and the northeast tower was added by Jasper Tudor, who assumed the lordship of Cardiff after the accession of his nephew, King Henry VII of England. During the English Civil War, the cathedral was overrun by Parliamentarian troops, and by 1720 the southwest tower was in a state of collapse. In 1734, work began on a new cathedral, nicknamed the "Italian Temple", which was used for a hundred years but never completed and now lies in a state of ruin.

During the 19th century, when the Bishop of Llandaff began, for the first time, to reside in his diocese, the cathedral was extensively restored, the tower rebuilt and a spire added. A triptych by Dante Gabriel Rossetti was designed for use as a reredos, and new stained glass windows were designed by Sir Edward Burne-Jones and Ford Madox Brown.

The cathedral school which existed from the time of Queen Elizabeth I of England until about 1700 was re-established in 1880.

On the evening of January 2, 1941 during World War II a German bomb fell beside the cathedral, causing massive destruction including that of the organ, only back in service since 1938. Of British cathedrals, only Coventry Cathedral was damaged more.

Major restorations and reconfigurations were carried out under architect George Pace of York, and the building was back in use in June 1958. The Queen attended a service celebrating the completion of the restoration on August 6, 1960. The Welch Regiment memorial chapel was constructed, and Sir Jacob Epstein created the figure of Christ in Majesty which is suspended above the nave on a concrete arch designed by George Pace .