James Biggs, a Calvinistic Baptist, who had been a member of the Back Street Baptist Chapel in Trowbridge before studying at Bristol Academy became minister of the Presbyterian chapel in Devizes. Shortly after this seceders from the Old Baptist chapel joined the Presbyterians for worship in their Sheep Street chapel and the establishment of the New Baptist Church can be dated from the pastorate of Biggs. In 1807 the two groups agreed to take communion together and in 1820 they became the 'United Society' although their home was still called the Presbyterian chapel.
The Baptists were growing in numbers and in 1848 the two groups formally united. In 1851 it was resolved to build a new chapel as a Baptist Church and invite the Presbyterians to occupy it. The chapel was opened in 1852, in Sheep Street next to the Presbyterian chapel, with seating for 700 and a schoolroom. This was during the pastorate of Charles Stanford who drew large congregations, including wealthy townspeople. He evangelized the area, introduced cottage preaching and later became a national Baptist leader. In 1851 the average congregation was 260 but on census Sunday there were 344 in the morning and 404 in the evening. By 1852 the congregation had doubled in size.
The old meeting house was demolished and the site added to the burial ground of the chapel. In 1874 the schoolrooms were enlarged and there were restorations of the chapel in 1901, when gas lighting was introduced, and in1927, when electricity was provided. The roof was reslated in the 1960s and there were many improvements in the 1970s. In 1978 and 1988 the Baptist Housing Association built the adjacent flats, partly on church land. In 1989 a major improvement scheme was carried out.