Bushfires are landscape-scale disturbances that trigger secondary hydrological, geomorphological and biogeochemical responses, particularly when followed by major rainfall and flood events. Widespread hillslope erosion and debris flows are known to occur after fires and floods, causing water quality issues downstream, but the geomorphic responses of rivers to flood pulses and elevated sediment supply following fires are relatively poorly understood. The Wadbilliga River and its catchment, a major tributary of the Tuross River on the south coast of New South Wales (NSW), were severely burned in the Badja fire during the ‘Black Summer’ of 2019/20. Analysis of satellite imagery and UAV-derived digital elevation models, combined with field surveys and sampling, allowed investigation of the dramatic response of the Wadbilliga River to the bushfire and subsequent flooding from 2020-2022. Significant erosion and channel expansion occurred and in several reaches the previously single-thread river developed an anabranching or wandering gravel bed planform where sections of the floodplain were stripped and reworked. These changes are associated with increased runoff and sediment supply from hillslopes and upstream, elevated stream power, and reduced hydraulic roughness following riparian vegetation loss. The findings highlight the sensitivity of bed and bank stability in post-fire environments and demonstrate how coupled disturbances can rapidly alter channel morphology and connectivity. Improved understanding of these processes is important for hazard assessment, post-fire recovery planning, and river and wetland management in fire-prone landscapes.