St Andrews Major (Welsh: Saint Andras) is a village and parish in the community of Dinas Powys in the Vale of Glamorgan, between Barry and Cardiff in south-eastern Wales.

Garnhill House (and Estate), occupying the north of the hamlet, is a Grade II listed building[1] with terraced gardens exhibited at the Royal Academy in 1904, [2] and has been occupied by the Green family for hundreds of years, expanding the Estate piecemeal.

The surrounding soil of the parish is a strong, brown, dry earth, well adapted for grain of all kinds.

It is sometimes subject to partial inundation from the overflowing of a small stream, called Dinas Powis brook, which runs through the south-eastern part of the parish towards the south, and empties itself into the Bristol Channel, between the parishes of Cadoxton and Sully, which lie between St Andrews and the channel.

At the east end of the north aisle, parallel with the chancel, is a private chapel, anciently the property and burial-place of a respectable family, named Rowel, long since extinct, and the Bouville family who were owners of a great part of the parish.