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. As a result of the damage done by bombing during World War II, further restoration was required. 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.
The cathedral school which existed from the time of Queen Elizabeth I of England until about 1700 was re-established in 1880.