The church sits on the edge of the Fal estuary, known as Carrick Roads at this point. The lann, or churchyard, is east of Mylor Churchtown, and slopes steeply down to the north towards the water’s edge. The churchyard is lushly planted, and the church sits in a hollow at the foot of a steep path below the entrance.

The surviving Romanesque elements suggest that the original church was built around the beginning of the 12thc., which would make this church one of the earliest Norman buildings in the county. The plan of the church was probably cruciform, but only the N transept remains.

The nave and N transept of the church follow the plan of the original cruciform church, and the N entrance employs the original Romanesque doorway. The N transept also contains Romanesque stonework. A Romanesque doorway has been reconstructed in the W gable wall using original fragments, possibly during the Victorian restoration.

The church was restored in 1869-1870 following a lightening strike. A small cross set above the S porch entrance may be Romanesque.

Mylor lay in the Episcopal Manor and Peculiar Deanery of Penryn and was the Mother church of Mabe.

The stone monolith east of the S porch (the Cross of St Mylor) is, at 5.4 m overall length, the tallest wheel-headed pre-Christian cross in Cornwall, and suggests there was a place of worship here prior to the Norman conquest.

An unusual feature of the church is a second tower, further west and higher than the church. It was built in 1636 as a belfry, and has a 19thc. upper storey which probably acted as a landmark for shipping.