A recent Hydrometeorological calamity has struck the Republic of Kenya, which shifted off a deep, multi-year drought to a catastrophic El Nino-accelerated and enhanced flooding of 2024-2025. The incidences have highlighted the urgency to have high-resolution spatial data to guide the reduction of disaster risks and humanitarian response. The project was created under the Legacy Project developing humanitarian open street map (HOT) Community Working Group (CWG) Mentorship 2025 and present a nationwide flood risk analysis of Kenya. This paper uses a Geographic Information System (GIS) and Multi-Criteria Decision Analysis (MCDA) model to integrate six factors with high impact, including rainfall intensity, elevation, slope, Land Use/Land cover (LULC), proximity to water body and proximity to road networks. The study reclassifies these parameters according to the hydrological and anthropogenic impact on them using weighted overlay methodology in order to generate a final flood risk map with five classes (Very High, High, Moderate, Low, and Very Low). Through the analysis, the high-risk areas are highly concentrated in the low-lying river basins and informal urban settlements whereby there is high concentration of accumulated rainfall and inadequate drainage and exposure. The results give the OpenStreetMap community and agencies of disaster management a strategic platform to focus on anticipatory efforts, improve field data collection, and improve resiliency of vulnerable communities