Biochar is an appropriate and value-added strategy for treating heavy metal-contaminated water in urban and industrial wastewaters. In this study, an innovative precursor based on chicken manure is used to produce biochar for As(III) removal. The modified biochar (MBC) was fabricated by the pyrolysis process and characterized by FT-IR, SEM, EDS, and TG-DTA analyses. Subsequently, the effect of pH, contact time, dosage of nanoadsorbent, and recycle performances have been studied for As(III) removal from wastewater. The results revealed that the optimum condition to achieve high adsorption capacity (98% As(III) removal) is at 1.5 g L −1 adsorbent dose, pH ~ 7.8, and during 300 min, as well as MBC was capable to use and recycle at least 10 times without considerable adsorption reduction, confirming the high stability of the nanoadsorbent in the exposure of wastewaters. Finally, a possible adsorption mechanism is proposed based on ion-exchange and the participation of electrostatic attractions of hydroxyl and carbonate groups.