The church was founded by St Collen from whom the town derives it's name. St Collen was a monk who lived in the 6th/7th Century, records are unclear as to the exact dates and much of what has been written about him is based on legend. It is said that he arrived in the area by coracle and was an Irish warrior and religious figure who also lived for a time as a hermit on Glastonbury Tor.
Collen gave his name to the town of Llangollen ('llan' for a church enclosure, and 'gollen' for Collen).
The original church built by St Collen and his monks would have been a very crude construction. In Norman times a 'new' church was built alongside.
In 1749 the churches wooden tower was replaced using stones from the newly demolished original church. A major extension in 1863 saw the south aisle added and the building extended eastwards to provide the chancel, clergy vestry and organ chamber.
The tower houses a belfry with eight bells hung to celebrate Queen Victoria’s Golden Jubilee in 1887. The most remarkable feature of the church is the oak hammer beam roof of the central nave. An earlier roof was destroyed in a fire in about 1522.
A tomb-shrine to Collen stood in the churchyard until the 19th century, but it was demolished to create space for the current west tower. The core of the church dates to the 13th century.