The study assessed the flood vulnerability of developed properties (DP) in Port Harcourt Metropolis, Rivers State, Nigeria. The study made use of DP data obtained from the open street map, and the combination of landuse/ landcover map obtained from Landsat imagery of 2020, soil texture data, elevation data, and proximity to the active river channel. Descriptive statistics were used for data analysis. Findings showed that 44014 DPs were estimated in Port Harcourt Metropolis. Results showed that the spatial extent of flood lowly vulnerable areas in Port Harcourt Metropolis was 60.78 sq. km (13.22%), moderately vulnerable areas were 259.72 sq km (56.51%) and highly vulnerable areas were 139.14 sq. km (30.27%). Furthermore, 3977 (9.04%) of DP were lowly vulnerable to flood, 34754 (78.96%) were moderately vulnerable to flood and 5283 (12%) were highly vulnerable to flood in the study area. The study can be concluded that the number of developed properties in the Port Harcourt Metropolis varied based on different flood vulnerability levels as more of them were found within the moderate vulnerability levels. Based on the findings, the study recommended that all the developed properties lying in the high flood vulnerability level should be relocated to better locations or at least conform to ways of guiding against the effect of flood on the developed properties; and also periodic enlightenment of the effect of flood to the public would help a lot of preventing people from constructing their house in the highly and moderately flood vulnerable levels.