The Division of Mayo is an Australian electoral division located to the east and south of Adelaide, South Australia. Created in the state redistribution of 3 September 1984, the division is named after Helen Mayo, a social activist and the first woman elected to an Australian University Council. The 9,315 km2 rural seat covers an area from the Barossa Valley in the north to Cape Jervis in the south. Taking in the Adelaide Hills, Fleurieu Peninsula and Kangaroo Island regions, its largest population centre is Mount Barker. Its other population centres are Aldgate, Bridgewater, Littlehampton, McLaren Vale, Nairne, Stirling, Strathalbyn and Victor Harbor, and its smaller localities include American River, Ashbourne, Balhannah, Brukunga, Carrickalinga, Charleston, Cherry Gardens, Clarendon, Crafers, Cudlee Creek, Currency Creek, Delamere, Echunga, Forreston, Goolwa, Gumeracha, Hahndorf, Houghton, Inglewood, Kersbrook, Kingscote, Langhorne Creek, Lobethal, Macclesfield, McLaren Flat, Meadows, Middleton, Milang, Mount Compass, Mount Pleasant, Mount Torrens, Mylor, Myponga, Normanville, Norton Summit, Oakbank, Penneshaw, Piccadilly, Port Elliot, Second Valley, Springton, Summertown, Uraidla, Willunga, Woodchester, Woodside, Yankalilla, and parts of Birdwood, Old Noarlunga and Upper Sturt.

Helen Mary Mayo was an Australian medical doctor and medical educator, born and raised in Adelaide. In 1896, she enrolled at the University of Adelaide, where she studied medicine. After graduating, Mayo spent two years working in infant health in England, Ireland and British India. She returned to Adelaide in 1906, starting a private practice and taking up positions at the Adelaide Children's Hospital and Adelaide Hospital.