Wallasey is a town in the Metropolitan Borough of Wirral, Merseyside, England. It is at the mouth of the River Mersey, on the north-eastern corner of the Wirral Peninsula. It lies within the historic county boundaries of Cheshire, and became part of Merseyside in 1974. At the 2021 Census, the built up area as defined by the Office for National Statistics had a population of 85,610.