A high-resolution impact-based early warning system for riverine flooding is presented, demonstrating the potential of such systems to improve disaster preparedness and response. The system integrates near-real-time inundation and impact forecasts with associated uncertainties, providing valuable information for risk-based decision-making. The study uses a hindcast of the 2021 European Summer Flood to illustrate the system's capabilities, offering a 17-hour lead time for informed actions. Flooding is a significant natural hazard affecting billions globally, with climate change exacerbating its frequency and severity. Despite advances in flood forecasting, operational systems often fail to provide accurate, timely information for effective response. The study highlights the need for impact-based forecasts that consider both physical and socio-economic factors. The proposed system includes a comprehensive forecasting chain involving meteorological data, numerical weather prediction, hydrological models, and high-resolution hydrodynamic simulations. The system provides detailed inundation maps and impact indicators, enabling more precise and timely emergency responses. The study also addresses challenges in computational efficiency, uncertainty propagation, and the integration of impact forecasts into operational systems. The effectiveness of the system is demonstrated through comparisons with official forecasts and benchmark data, showing its potential to enhance flood risk management. The study underscores the importance of transparent communication of forecast uncertainties and the need for interdisciplinary collaboration to improve flood forecasting and warning systems. The findings highlight the value of high-resolution, impact-based forecasting in enhancing disaster preparedness and reducing socio-economic impacts of flooding.A high-resolution impact-based early warning system for riverine flooding is presented, demonstrating the potential of such systems to improve disaster preparedness and response. The system integrates near-real-time inundation and impact forecasts with associated uncertainties, providing valuable information for risk-based decision-making. The study uses a hindcast of the 2021 European Summer Flood to illustrate the system's capabilities, offering a 17-hour lead time for informed actions. Flooding is a significant natural hazard affecting billions globally, with climate change exacerbating its frequency and severity. Despite advances in flood forecasting, operational systems often fail to provide accurate, timely information for effective response. The study highlights the need for impact-based forecasts that consider both physical and socio-economic factors. The proposed system includes a comprehensive forecasting chain involving meteorological data, numerical weather prediction, hydrological models, and high-resolution hydrodynamic simulations. The system provides detailed inundation maps and impact indicators, enabling more precise and timely emergency responses. The study also addresses challenges in computational efficiency, uncertainty propagation, and the integration of impact forecasts into operational systems. The effectiveness of the system is demonstrated through comparisons with official forecasts and benchmark data, showing its potential to enhance flood risk management. The study underscores the importance of transparent communication of forecast uncertainties and the need for interdisciplinary collaboration to improve flood forecasting and warning systems. The findings highlight the value of high-resolution, impact-based forecasting in enhancing disaster preparedness and reducing socio-economic impacts of flooding.