Chemically modified corncob biochar was prepared to remove methyl violet, an organic dye, from simulated wastewater. Modern analytical methods, including SEM, FT-IR, BET/pore, etc., indicated that the porous biochar exhibited excellent characteristics, with a high specific surface area (989.14 m²/g), a large pore volume (0.61 cm³/g), and abundant functional groups on its surface. Consequently, it achieved high removal efficiency for methyl violet, with an adsorption capacity of 290.7 mg/g and a removal rate of 92.4% at high concentrations. The Pseudo-first-order and Temkin models can effectively simulate the kinetic and isotherm adsorption processes of BioPNa for MV, with R² > 0.99, indicating physicochemical composite processes as the adsorption mechanisms, including pore filling, electrostatic attractions, hydrogen bonds, and π-π interactions. The porous material also demonstrated high stability and reusability after five adsorption-desorption cycles. Therefore, it can be used as a low-cost, high-efficiency material for effectively removing methyl violet from wastewater.