Waterfall Gully is an eastern suburb of the South Australian capital city of Adelaide. It is located in the foothills of the Mount Lofty Ranges around 5 km (3.1 mi) east-south-east of the Adelaide city centre. For the most part, the suburb encompasses one long gully with First Creek at its centre and Waterfall Gully Road running adjacent to the creek. At the southern end of the gully is First Falls, the waterfall for which the suburb was named. Part of the City of Burnside, Waterfall Gully is bounded to the north by the suburb of Burnside, from the north-east to south-east by Cleland National Park (part of the suburb of Cleland), to the south by Crafers West, and to the west by Leawood Gardens and Mount Osmond.

Waterfall Gully is connected to the major Adelaide thoroughfare Greenhill Road by Waterfall Terrace and Glynburn Road, and cars are the preferred mode of transport in the suburb. According to the Australian Bureau of Statistics 71.9% of residents in the census area employed private vehicles for their commute to work. Only a small proportion (1.3%) walked to work and but 1.2% cycled, while only 3.6% of Waterfall Gully residents travel to work by bus. The closest bus route for Waterfall Gully is the 142 bus, provided by the multi-service Adelaide Metro.