Water hyacinth (Eichhornia crassipes) is an aquatic weed that is causing numerous adverse effects on freshwater bodies. Developing countries are still battling on how to control the growth of this weed without damaging other aquatic lives important to man. Literatures have revealed that most developing countries are still discharging untreated sewage containing heavy metals into waterbodies due to economic and technical constraints in handling conventional methods of treating heavy metals. Hence, the research investigated the possibility of using water hyacinth to adsorb heavy metals (Ni2+ and Cr3+) from sewage before discharging into waterbodies in order to solve two major problems faced in the aquatic environment, at minimal cost. This was achieved by using the said weed (water hyacinth) to treat Ni2+ and Cr3+ solutions prepared in the lab. Results showed that the adsorption process for both ions occurred on heterogeneous surfaces while the mechanism of adsorption followed Pseudo 2nd–order kinetics. The Freundlich, Langmuir and Temkin adsorption capacities for Ni2+ are 19.6925l/g, 0.7470l/mg and 1.1093l/mg respectively while for Cr3+ are 16.814l/g, 0.7011l/mg and 0.9623l/mg respectively. However, the heat of sorption for Ni2+ is 96.906KJ/mol while that of Cr3+ is 98.749KJ/mol. Furthermore, FT-IR analysis identified seven functional groups involved in the binding sites with more of hydroxyl group (O–H) from alcohol and carboxylic acid. It was concluded that water hyacinth could be used as a potential bio-adsorbent of metal ions.