Pollution of water sources with heavy metals is one of the most important global environmental issues. Even though there are many physical and chemical methods for removing heavy metals from contaminated water, in recent years cost-effective and environmentally friendly techniques such as phytoremediation and biosorption are used to remove heavy metals from water. In this study, phytoremediation and biosorption potential of Lythrum salicaria L. for nickel removal from aqueous solutions were investigated. Phytoremediation experiments were conducted at 10% Hoagland solution with 0, 10, 15, 20, 25, 50, and 100 mg/L nickel, and pH levels of 5, 6, and 7 to determine the accumulation of nickel in vegetative parts of L. salicaria. Phytoremediation results indicated that maximum Ni (II) accumulation by L. salicaria was at pH 7 with 10 mg Ni/L and distribution of Ni (II) was in the root (3,737.8 mg/kg DW) > shoot (697 mg/kg DW) > leaf (418.4 mg/kg DW) of L. salicaria. On the other hand, the effect of pH, biomass dosage, contact time, and initial Ni (II) concentration on the biosorption potential of L. salicaria roots was investigated in a batch system at room temperature. Optimum conditions were achieved at pH 7 with the biomass dosage of 6 g/L at an equilibrium contact time of 40 min. Equilibrium data was adapted to Langmuir and Freundlich isotherm models to find the best-fitting model. The Langmuir isotherm model described the biosorption process best with a maximum monolayer sorption capacity of 9.1580 mg/g for Ni (II) ions.