TreLlewelyn is one of the ancient townships of Flintshire, which later became part of Denbighshire. It was mentioned in the Domesday Book as part of the holdings of Robert, the nephew of Hugh Lupus, Earl of Chester. Over time, TreLlewelyn, along with other townships like Crickin, Yscawen, Pentre, Brynbychan, Brynywal, Cefndy, Brynhedydd, Rhydorddwy, and Rhyl, formed the mother parish of Rhuddlan1. In 1844, the townships of Rhyl and Brynhedydd were transferred to the newly formed parish of Rhyl. More land was transferred from Rhuddlan to Rhyl after the opening of the district church of St. Ann in 1896.