Currently, the social stock and scrappage of printers are both huge. The waste toner collected from the ink cartridges is difficult to degrade and has a small particle size, so the common treatment method is landfill, resulting in environmental pollution and resource wastage. This research aims to exploit the abundant presence of carbon black and magnetic powder in waste toner to synthesize nitrogen and oxygen co-doped magnetic carbon materials. It speculates that the amidation reaction between with the amino group of L-cysteine and the carboxylate group of waste toner in mild one-pot conditions leads to the incorporation of nitrogen and oxygen atoms. It significantly enhances the hydrophilicity of waste toner reducing the contact angle from 138.1° to 41.0° and provides active sites for the adsorption of Pb(II). Building upon this material, a novel approach combining magnetic solid-phase extraction with graphite furnace atomic absorption spectrometry has been developed for ultrasensitive lead analysis. This method demonstrates the detection limit of 43 ng L-1 with an RSD of 7.1% (CPb(II) = 0.2 μg L-1) and has been successfully employed for the analysis of trace lead in tap water, lake water, urine, and serum. Furthermore, this material exhibits rapid adsorption kinetics, robust resistance to matrix interferences, and low cost, thereby offering a novel avenue for mitigating environmental contamination through the concept of "waste-to-waste" treatment.