Today, the common problem of all countries in the world is the presence of heavy metals in water, air and soil environments. Ni(II) is a pollutant belonging to the group of primary toxic and bioaccumulative heavy metals commonly found in industrial wastewater. In addition, recycling food waste such as mushroom stalk wastes (MSWs), which are released as a result of domestic use, instead of throwing them into the garbage cycle, is of great importance for the minimization of environmental pollutants. Therefore, the main aim of the study is to determine Ni(II) biosorption capacity by applying natural MSW to wastewater. Within the scope of the study, the purification efficiency of Ni (II) was evaluated with laboratory-scale batch biosorption experiments under a different MSW dose, contact time and pH conditions. To reveal the biosorbent qualities of the MSW used in the study, its surface morphology and functional structure were determined using FT-IR and SEM. According to the experimental data, the suitability of Langmuir and Freundlich isotherms, and pseudo-second-order and pseudo-first-order kinetics, was calculated. According to the optimum adsorption factors, the maximum removal efficiency and adsorption capacity of Ni (II) for MSW were determined. Experimental results show that MSW is an economical and easily accessible biosorbent material.