St Mellons Rural District is a defunct district council. It was established under the provisions of the Local Government Act 1894 from part of the existing Newport Rural Sanitary District. It comprised the parishes of Bedwas, Bettws, Coedkernew, Duffryn, Graig, Henllys, Machen Lower, Machen Upper, Malpas, Marshfield, Michaelstone-y-Fedw, Peterstone Wentloog, Rogerstone, Rumney, St Brides Wentloog, St Mellons and St Woolos in the administrative county of Monmouthshire. Initially, the St Mellons Rural District Council also administered two parishes in Glamorgan: Llanvedw and Rhydygwern, which had also formed part of the sanitary district. The Glamorgan parishes were annexed to Llandaff and Dinas Powis Rural District in 1895.