The parish church is located in OS Grid Square SW8032 and was dedicated to King Charles the Martyr in 1665. It must be remembered that in the early 1600's there were no more than eight houses in Falmouth, and by 1665 this number had increased to only 200. Even as late as 1721 no house lay to the west of Market Street and no road was made up the moor. Sir Peter Killigrew in 1660 planned his church to be the centre of what he envisaged as a growing town, and this has come about in the church's three hundred years of history, with Falmouth's building estates now reaching out towards the parish of Budock.
On August the 29 1662, Sir Peter measured out the ground which was to be devoted to the Church and a ministers house and workers began to dig the foundations. The building was finished on February 21st, 1664 having taken only 18 months to complete. The first sermon was preached in the finished Church by John Bedford, who was appointed as the first rector, his chosen as his text being: Gen: 33; 20 etc. On March 17 1663 the first sacrements were administered, and on August 22nd, 1665, the church was consecrated by Dr Seth Ward, Lord Bishop of Exeter. It was built at the expense of King Charles II, the Duke of York (later James II) and other distinguished persons. in memory of their father - the executed King Charles I.
The Records show that on the 26 November 1664 James Prowse, Gent, was the first to be buried in the Churchyard. The Rector John Bedford was forbidden to bury anyone else because the ground was not consecrated. On April the following year, he was permitted to resume burials by The Most Reverend C T Gilbert, Archbishop of Cantabury, and the Right Reverand ct Seth Bishop of Exon (Exeter). From 1663 to 1877 the parish was part of the Diocese of Exeter; from 1877 onwards it became part of the Diocese of Truro.
The church comprises a chancel, nave, north and south aisles, north, south and west galleries, and a vestry. The central roof is supported by eight lofty Ionic columns of granite, four on each side, assisted by wooden pillars. In 1684 extensions were made to the east and west. A chancel was added and the lowest part of the tower was built. In 1695 a gallery was built at the west end at the joint cost of Sir Peter Killigrew and Mr Bryan Rogers; also in that year, another gallery was built on the north aisle by voluntary contributions, and in 1702 one was built in the south aisle. An organ was erected in 1703 which was replaced in 1798. The tower was raised another stage in 1738 when it acquired a 12-hundredweight bell, and was raised again by another stage in 1800 for the reception of a clock. Three additional bells were added in 1861. The tower is finished with battlements and pinnacles.
The population of Falmouth had grown to about 7000 by 1813, so the 1684 chancel was demolished. At the same time, the church was lengthened eastward by one-third of its whole length, and the chancel was then rebuilt. In 1861, the flooring of the church was renovated. In 1896 another major reconstruction began. The three pitched roofs and the galleries were removed and the walls raised. Three new barrel ceilings in ornamental plaster work were installed. The building was back in use within a year. An organ chamber was installed in 1915, when the previous space occupied by the organ became the Warrior Chapel. A new window was added to this chapel which was dedicated as a war memorial in 1928. A baptistry was formed in 1936.
There are a south door, a north porch, a priest's door and a vestry door. The bells have now been replaced by an eight-bell carillon.