Flood damages have increased in recent years; while this is partly due to anthropogenic climate change, it has been exacerbated by population growth and economic development taking place in regions of high vulnerability. Onrush water flow from upstream rivers is also responsible for flash floods in these regions. In particular, the north-eastern wetland region of Bangladesh is extremely vulnerable to flash floods, which damage crops, property, and infrastructure every year. The flash flood of 2022 alone has surpassed most of the previous records. The main purpose of this study is to develop and evaluate a methodology for the delineation of flash flood hazard zones considering the recent year flash flood of 2022, 2020 and 2018. After reviewing relevant literature, flood affected area and delineation of flood hazard zone in the study region is investigated through remote sensing approach. The Sentinel-01 SAR images were used to generate inundation extents and SRTM data, JRC and Landsat satellite images were used for flood hazard classification using Google Earth Engine (GEE) and ArcGIS Pro. The findings identified 56% of the Sylhet division as inundated with significant inter-district variability in flood hazards: Sunamganj (82%), Sylhet (62%) and Moulavi Bazar (33%) districts emerged as affected. In addition, having 57% affected area, Habiganj have 30 union which was flashed more than 80% of its land. At Sunamganj, there was 301405.4 Hectare area flashed and 1374939 female population was affected which represents more than 50% of total population of Sunamganj district. With the onslaught of climate change, the risk and uncertainty of flash floods will increase. As such, this paper identifies zones of high risk to inform future regulations of spatial planning and interventions. The findings will be useful for involved authorities and policymakers while taking explicit and efficient flood damage reduction strategies in the future.