The application of sustainable stormwater management system in waterlogging areas of urbanized rncatchments is the most effective method that helps to control surface stormwater runoff caused by rnrecurrent and extreme rain events. Applying a bio-retention system for flood reduction through rninfiltration and evapotranspiration processes will help to create an attractive urban street with better rnenvironmental performance. Since cities are becoming more impervious, the stormwater runoff rnincreases and will affects the downstream land and water bodies by flooding. In Addis Ababa, applying rna sustainable stormwater management system is a timely act due to the ongoing rapid urbanization and rnincrement in impervious surfaces that result in stormwater runoff that causes flooding and surface rnwater pollution. In this regard, innovative and flat terrain considerate design responses are needed in rnlow-lying plains with difficulties to apply conventional pipe-based drainage systems. The design rnintervention will reduce the waterlogging effect occur due to extreme rain events. The objective of the rnresearch is to apply curb-extensions as a bio-retention system for sustainable stormwater management rnof waterlogging local streets in the low-lying residential areas of Addis Ababa. Specifically, the study rnidentified areas affected by peak stormwater flow that creates a waterlogging problem over local streets rnof the case study area. A sustainable design solution is proposed by considering the infiltration, rnretention, and evapotranspiration capacity of curb-extensions. The study identified flooding and rnwaterlogging areas in the city, at the river catchment, and in the study, site using hydrological and rnspatial data. Using ArcGIS-based hydrologic analyst tools, blue spots located along the flow direction rnof the streams identified as depressions usually experienced an overflow of stormwater and rnwaterlogging. To minimize the risk of waterlogging, a sustainable design solution as a curb extension rnsystem designed by estimating the water balance from the actual water holding capacity of natural rndepression (blue-spot) and the stormwater runoff generated from the catchment area that naturally rndrained into the specific blue-spot. The curb-extension system was designed as a bio-retention and rnstreetscape element by modifying the native soil, gravel fill, water intake plants on the top of the systemrnfor infiltration and retention purpose. In this regard, the designed curb extension will substantially rnmanage the highest intensity of precipitation (40 mm/hr) of 10 years of rain event from IDF curve of rnAddis Ababa. The design reduces the volume of stormwater runoff from 22.895 m3 to 8.477 m3, which rnis 62 % of runoff. The study concludes that if the municipality of Addis Ababa develops a curb extension system over the local streets of the entire neighborhoods affected by waterlogging, the rnflooding problem will be reduced substantially with more greening & environmental benefits. The rnsystem will also contribute to the reduction of downstream flooding by minimizing stormwater runoff rnflowing into the Akaki river system. As a multifunctional drainage design facility, the system has the rnpotential to create a green street that helps to improve the standard of living and boost the rnenvironmental quality of the area. Finally, the study recommended further study on the upscaling of rnproposed curb-extension by developing more empirical and experimental settings as a pilot project. rnThe pilot projects will help the city to consider the curb-extension system for the greening, drainage rndesign, and urban planning practices. Moreover, the tests and demonstration works will justify its rncompetency for improving the livability and livelihood of the local people within urban settings that rnwere frequently affected by waterlogging.