Selby is a market town and civil parish in North Yorkshire, England, 12 miles south of York on the River Ouse. At the 2021 Census, it had a …Selby is a market town and civil parish in North Yorkshire, England, 12 miles south of York on the River Ouse. At the 2021 Census, it had a population of 17,193. The town was historically part of the West Riding of Yorkshire; from 1974 until 2023, it was the administrative centre of the Selby District.