Mayo is a census-designated place (CDP) in Anne Arundel County, Maryland, United States. The population was 8,298 at the 2010 census. The Mayo CDP of 2010 includes all of the area that used to be counted as the Selby-on-the-Bay CDP. The beach in Mayo used to be a popular weekend resort.
Mayo is located at 38°53′36″N 76°30′16″W / 38.89333°N 76.50444°W / 38.89333; -76.50444,(38.893264, -76.504371) south of Annapolis. It occupies a peninsula between the South River to the northeast and the Rhode River to the southwest, both of which are tidal arms of Chesapeake Bay. It is bordered by the CDP of Edgewater to the northwest, and (across the South River) by the CDP of Annapolis Neck to the northeast. Saunder's Point, Shoreham Beach, Beverly Beach, Cloverlea, Turkey Point, Holly Hill Harbor, Selby Beach, and Cape Loch Haven are some of the neighborhoods found in Mayo.
According to the United States Census Bureau, the CDP has a total area of 9.5 square miles (24.5 km2), of which 5.6 square miles (14.6 km2) is land and 3.8 square miles (9.9 km2), or 40.47%, is water.