This study examines the spatial extent of coastal urban development and its potential sensitivity to sea-level rise. The main aim of the study is to critically examine the extent of growth in Eti-Osa over time, and the potential impacts of sea leve rise. Landsat Enhanced Thematic Mapper Plus (ETM+) imageries of years 2000 and 2015 were used to evaluate the different land use type identified. Post-classification change detection method was used to evaluate the output of the maximum likelihood supervised classification analysis done. This was also used to estimate the changes induces through urban development on the environment which accounts for the biodiversity loss. ASTER GDEM 2 imagery of 2011 was used to generate the elevation data used for the inundation analysis. Thus, both Land use map of Eti-Osa in 2015 and the down scaled Sea-level rise scenarios (at 0.5 to 15 meters) were used for the inundation mapping. Results obtained from this research affirms that indeed EtiOsa has been subjected to gross urban expansion giving room for diverse forms of environmental degradation among which are huge replacement of natural land cover with built-up, reclamation of wetlands and sand filling of water bodies. This basically illustrates growth but also the risk that accompanies the advent of excessive alteration of natural ecosystem as Sea-level rise projections imply in this research.