The Statute of Rhuddlan (Welsh: Statud Rhuddlan), also known as the Statutes of Wales (Latin: Statuta Walliae or Valliae) or as the Statute of Wales (Latin: Statutum Walliae or Valliae), was a royal ordinance by Edward I of England, which gave the constitutional basis for the government of the Principality of Wales from 1284 until 1536.

The statute followed the Conquest of Wales by Edward I and the killing of the last Welsh prince to rule the whole Principality, Llywelyn ap Gruffudd in 1282. The statute introduced English common law to Wales, but also permitted the continuance of Welsh legal practices within the Principality. The statute also introduced the English shire system to the Principality of Wales. Prior to the statute, the Welsh principalities were ruled by Welsh law and the native Princes of Wales.

The Prince of Gwynedd had been recognised by the English Crown as Prince of Wales in 1267, holding his lands with the king of England as his feudal overlord. It was thus that the English interpreted the title of Llywelyn ap Gruffudd, Lord of Aberffraw, which was briefly held after his death by his successor Dafydd ap Gruffudd. This meant that when Llywelyn rebelled, the English interpreted it as an act of treason. Accordingly, his lands escheated to the king of England, and Edward I took possession of the Principality of Wales by military conquest from 1282 to 1283. By this means the principality became "united and annexed" to the Crown of England.^{[page needed]}

Following his conquest Edward I erected four new marcher lordships in northeast Wales: Chirk (Chirkland), Bromfield and Yale (Powys Fadog), Ruthin (Dyffryn Clwyd) and Denbigh (Lordship of Denbigh); and one in South Wales, Cantref Bychan. He restored the principality of Powys Wenwynwyn to Gruffydd ap Gwenwynwyn who had suffered at the hands of Llewelyn, and he and his successor Owen de la Pole held it as a marcher lordship. Rhys ap Maredudd of Dryslwyn would have been in a similar position in Cantref Mawr, having adhered to the king during Llewelyn's rebellion, but he forfeited his lands by rebelling in 1287. A few other minor Welsh nobles submitted in time to retain their lands, but became little more than gentry.

The English Crown already had a means of governing South Wales in the honours of Carmarthen and Cardigan, which went back to 1240. These became counties under the government of the Justiciar of South Wales (or of West Wales), who was based in Carmarthen. The changes of the period made little difference in the substantial swathe of land from Pembrokeshire through South Wales to the Welsh Borders which was already in the hands of the marcher lords. Nor did they alter the administration of the royal lordships of Montgomery and Builth, which retained their existing institutions.

The statute also divided Wales into administrations of government via shires which were essentially provinces of the English crown. Prior to the statute, the Welsh principalities were ruled by Welsh law and the native Princes of Wales, the last prince to rule the whole Principality being Llywelyn ap Gruffudd, killed in an ambush by the English in 1282.

The statute was not an act of Parliament, but rather a royal ordinance made after careful consideration by Edward I on 3 March 1284. It takes its name from Rhuddlan Castle in Denbighshire where it was first promulgated on 19 March 1284. The Statute was superseded by the Laws in Wales Acts 1535 and 1542 when Henry VIII made Wales unequivocally part of the "realm of England".

The statute was formally repealed by section 1 of, and the schedule to, the Statute Law Revision Act 1887 (50 & 51 Vict. c. 59).