Set on a hill, in the centre of the village, commanding panoramic views of North Pembrokeshire and the coast, Mathry has claims to be one of the oldest settlements in Pembrokeshire. 

The present church, the fifth to occupy the site, dates from 1869. It was designed by R K Penson whose work is today considered of significance as the achievements of Victorian architecture increasingly gain the attention and re-evaluation they deserve. Penson's church was first restored in 1902.

The previous church had a spire, as mentioned in Richard Fenton's A Historical Tour Through Pembrokeshire (1811). The church in Fenton's day 'was formerly dignified by a steeple, serving as a landmark for mariners from its position on this conspicuous eminence, an exposure that proved the means of its destruction, it being blown down in a storm'. Penson's plan for the church included a spire, but insufficient funds meant that this was never built.

In the west wall of the churchyard there are two inscribed stones from the ninth century, both bearing a simple cross in a circle. One was found in the wall of the farmhouse at Rhoslanog and in all probability this came from an earlier burial ground which is known to have existed in a field at a short distance to the south of this house. The second was removed from Tregidreg farm where is was used as a gatepost. A stone in the church porch belongs to an earlier period, probably fifth or sixth century. The inscription is cut in Ogham script and reads: 'Mac Cudicel son of Caticuus lies here'

This is the church of the Holy Martyrs. The twelfth century Book of Llandaff describes how St Teilo, walking beside the river Taf at Llanddowror rescued seven baby boys, whose father was too poor to provide for them. The saint baptised them and every day they received fish to eat from the river. Eventually they were sent to Mathry where for the rest of their lives they were known as the seven saints. In the 17th and 18th centuries a number of cist burials were discovered near the churchyard and these were instantly called the coffins of the martyrs.

Mathry was an important benefice of the diocese in medieval times, granted a market and hiring fair by King Edward III. The market had ceased by 1833 but the hiring fair, on 10th October, where local farmers who were looking  for male and female agricultural workers had an opportunity to listen to other local farmers who were looking for new agricultural workers for their farm, continued up until the Great War.