A Catholic presence began in Treforest soon after the Great Famine in Ireland (1840s), when many Irish immigrants arrived in South Wales. At the time, there was no place of worship in Treforest, and spiritual needs were catered for by clergy travelling in from Merthyr Tydfil and Aberdare. A school was founded in , though Aberdare continued issuing baptismal certificates for the district until 1868. The first St Dyfrig's (the saint was first referred to by his Latin name of Dubricius) was opened on Bridge Street in 1868. At first, the school was annexed to it, but in 1884 it moved to a new location, where it remained into the early 1960s.