Holy Trinity Church was established by John Rees, police constable at Pwll, who persuaded the Rev. David Jones to have a church built at the time he took up his ministry at Pwll. The vicar agreed, provided that Rees could provide a congregation. To begin with, the newly established congregation held their services in the front room of the police station, with Rees's wife playing the accompaniment on the harmonium. When the room became too small services moved to a schoolroom belonging tp the Pembrey school board. The first harvest service was held in 1903, with over 300 people present. The church was dedicated in 1905. The church and grounds were consecrated in 1932. Holy Trinity became part the new Parish of Burry Port with Pwll on 1st May 1959.

The land on which the church stands was donated by Mr Cyril Jones, squire of Cilymaenllwyd. The building was originally intended to be built of corrugated iron, but after consideration it was decided that a stone building would be sturdier and easier to maintain. The roof was originally covered with Ruabon tiles. The church was heated and ventilated by a new process patented by Arengo Jones. John Evans, a local builder and contractor designed a lectern of pitch pine.The lectern, communion table and pulpit were all made by Messrs Brown, Thomas and John at Erw Yard.

The churchyard boundary wall was built in 1906. The first burial was an eight-week old baby, Reginald John Lewis, in 1907. Central heating was installed in 1909. The war memorial was donated by Lady Catharine Stafford Howard in 1918. The chancel and porch were added in 1925. Electricity was also installed at that time. In 1935 a retaining wall was built on the north side of the church. The top part of the churchyard was donated by Lady Catharine Stafford Howard in 1953. In 1959 the original organ was replaced by a pipe organ. Electric heating was installed in 1961. In 1978 the pipe organ was replaced with a Livingstone electric organ, and the organ chamber was converted into an alter vestry.

Sources include:
www.llanelli-history.co.uk/churches

N Vousden, RCAHMW, 15 October 2012