This resource includes seabed backscatter data for South-west Corner Marine Park collected by Geoscience Australia during the periods 9 – 12 March 2020 and 27 January – 16 February 2021 on the charter vessel Santosha. The survey was undertaken as a collaborative project with the University of Western Australia, the University of Tasmania and the Australian Centre for Field Robotics (University of Sydney) and funded through the National Environmental Science Program Marine Biodiversity Hub, with co-investment by all partners and the Director of National Parks. The purpose of the project was to build baseline information for benthic habitats on the continental shelf in the marine park that will support ongoing environmental monitoring within the South-west Marine Park Network as part of the 10-year management plan (2018-2028). Data acquisition for the project included multibeam bathymetry and backscatter for an area covering 330 km^2 offshore from Cape Naturaliste to Cape Leeuwin coast, with underwater imagery of benthic communities and demersal fish collected by University of Western Australia on separate field deployments. This backscatter dataset contains a 4 m resolution 32-bit geotiff file of the survey area produced from the processed Kongsberg EM2040C multibeam sonar system data using the CMST-GA MB Process v15.04.04.0 (.64) toolbox software co-developed by the Centre for Marine Science and Technology at Curtin University and Geoscience Australia. For further information see: Giraldo-Ospina, A. et al., 2021. South-west Corner Marine Park Post Survey Report. Report to the National Environmental Science Program, Marine Biodiversity Hub.