A novel method incorporating electrochemical (EC) modification and one-step pyrolysis is developed to prepare sustainable Fe3O4-based magnetic adsorbent (EC-Fe3O4/BC) via pyrolysis of FeCl3-pretreated corn straw-derived biochar under an electric field generated by graphite electrode. Morphological characterization revealed a uniform dispersion of rod-like crystalline Fe3O4 nanoparticles in the inner and outer structure of biochar. The EC modification also introduced more oxygen-containing functional groups, which contributed to an outstanding Pb adsorption capacity (113 mg g(-1)) and fast kinetics (0.054 g mg(-1) h(-1)). Therefore, the EC modification is a simple and time-saving method to effectively fabricate magnetic biochar adsorbent for high-performance wastewater treatment.