This study highlights the essential role of geology in promoting sustainable urban planning, using the city of Derna as a case study following the catastrophic floods caused by Storm Daniel in September 2023. The disaster revealed a convergence of geological hazards such as flash floods, landslides, and coastal erosion intensified by climate change and unregulated urban expansion. These factors underscore the urgent need to integrate geological considerations into urban planning processes. A descriptive analytical approach was adopted, involving a review of previous studies and official reports, analysis of geological, topographic, and satellite data, and assessment of the geomorphological and hydrological characteristics of Wadi Derna. The study also incorporated field investigations, expert consultations, and comparative analysis of similar international case studies. The results indicate that karstic formations, steep slopes, alluvial fans, and construction within natural drainage channels significantly amplified the disaster’s impacts. The lack of prior geological and hydrological assessments contributed to unsafe urban development and heightened vulnerability to natural hazards. The study emphasizes that integrating geological data, hazard mapping, and advanced tools such as GIS and artificial intelligence is crucial for enhancing urban resilience, particularly during post-disaster reconstruction. The study concludes by recommending a geology-based sustainable planning framework, including detailed geological and hydrological mapping, early warning systems, enforcement of construction restrictions in wadi channels, and strengthened collaboration between geologists and urban planners to ensure safer and more sustainable urban development in Derna........................ Keywords:............Geology, Sustainable Urban Planning, Geological Hazards, Derna, Natural Hazards.