Mapping the extent and composition of important benthic habitats and demersal fishes is essential for effective spatial management of marine ecosystems. Here we propose a set of benthic and fish assemblage metrics and generate spatial distribution maps at a broad bioregional scale. These metrics have been informed using previous syntheses of stereo-video fish and habitat annotation data, and incorporate decades of fisheries science to select representative indicator species that are likely to respond to fishing pressures. We synthesised fish and habitat assemblage annotation data from 3,283 stereo-video deployments across south-western Australia along 2,600 km of coastline. We used generalised additive models, with full-subset model selection, to determine correlations between habitat and fish metrics and physical, environmental and anthropogenic predictors. Benthic habitat distributions were correlated with geomorphological features that were captured in the model as bathymetry-derived metrics, and fish metrics were correlated with roughness, the cover of reef and recreational fishing pressure. This synthesis demonstrates how stereo-video data can be used in conjunction with available bathymetry, environmental and human-use data to create benchmarks and spatial distribution maps of benthic and fish assemblage metrics at a large biogeographic scale.