[3] In AD 921, the Anglo-Saxon king, Edward the Elder, founded a burh named Cledematha (mouth of the Clwydd) at Rhuddlan.

Following the Conquest, in 1086, Rhuddlan was recorded in the Domesday Book as a small settlement within the hundred of Ati's Cross and in the county of Cheshire.

The town was thus where Edward I signed the Statute of Rhuddlan, laying down the way by which the Principality of Wales, created by the princes of Gwynedd, was to be governed.

In 2021 February, archaeologists from Aeon Archaeology announced the discovery of more than 300 stone age tools and artefacts in Rhuddlan.

Expert Richard Cooke believes that the remains were belong to people who was passing through and made camp by the river more than 9,000 years ago.