Graft copolymerization of polyacrylic acid (PAA) onto Acacia gum (AG) using erythrosine dye (ERY) in aqueous media combined with thiourea (TU) as a reducing agent under visible light was studied. The optimal grafting parameters were examined in terms of irradiation time and the concentrations of ERY, TU, AA, and AG. Grafting factors such as grafting percentage (GP%), grafting efficiency (GE%), as well as homopolymerization (HP%) all were determined. Graft products of PAA-g-AG copolymers were characterized using FTIR spectroscopy, X-ray diffraction, and thermal analysis. The highest GP (310%) was obtained through optimization of the grafting variables. The optimized graft product was crosslinked and used as a potential candidate for removing of methylene blue dye from an aqueous system.