Gawler is the oldest country town on the Australian mainland in the state of South Australia. It was named after the second Governor (British Vice-Regal representative) of the colony of South Australia, George Gawler. It is about 40–44 km (25–27 mi) north of the state capital, Adelaide, and is close to the major wine producing district of the Barossa Valley. Topographically, Gawler lies at the confluence of two tributaries of the Gawler River, the North and South Para rivers, where they emerge from a range of low hills.

Gawler is just over forty kilometres north of Adelaide city centre along Main North Road. Main North Road was the historic road to the Mid North region of South Australia. North of Gawler, the road is now known as the Horrocks Highway. The Sturt Highway runs northeast from the north side of Gawler, leading to Nuriootpa, the Riverland, Mildura and Sydney. The Barossa Valley Way runs east from the centre of Gawler into the Barossa Valley, and was the original route of the Sturt Highway. The Thiele Highway leads north between the Horrocks and Sturt Highways to Freeling, Kapunda and Morgan. The Northern Expressway is a new highway to the southwest providing a bypass of Gawler as part of the North–South Corridor, Adelaide which will eventually provide a non-stop road from south of Adelaide to Nuriootpa.