Deteriorating soil quality and decrease in vegetation abundance are grave consequences of open waste dumping which have resulted in growing public concern. The focus of this study is to assess the contribution of open waste dumping in soil contamination and its effect on plant diversity in one of the renowned green cities of Pakistan. Surface soil samples (n = 12 + 12) were collected from both the open waste dumping areas allocated by Capital Development Authority (CDA) and sub- sectors of H-belt of Islamabad city (representative of control site). The diversity of vegetation was studied at both sampling sites. Significant modifications were observed in the soil properties of the dumping sites. Soils at the disposal sites showed high pH, TDS and EC regime in comparison to control sites. Various heavy metal concentrations i.e., Lead (Pb), Copper (Cu), Nickel (Ni), Chromium (Cr) and Zinc (Zn) were also found to be higher at the dumping sites except for Cadmium (Cd) which had a higher value in control site. A similar trend was observed in plant diversity. Control sites showed diversified variety of plants i.e., 44 plant species while this number reduced to only 32 plant species at the disposal sites. This is attributed to changes in soil characteristics at disposal sites and in its vicinity areas.