Llandaff (Welsh Llandaf llan church + Taf) is a district of the city of Cardiff, Wales, and is also the name of a diocese of the Church in Wales, covering the most populous area of south Wales.

Llandaff Cathedral is the most prestigious of the Welsh dioceses. Much of its fabric dates from the 13th Century. One of its main modern points of interest is the aluminium figure of Christ in Majesty, by Jacob Epstein, which is suspended above the nave.

The area is served by rail at Llandaf railway station , and by local bus services 24, 25, 33, 33A, 60, 62 and 62A.