<p>Wealth out of Waste (WoW) approach has attracted considerable attention for its potential economic and environmental benefits. A novel method to synthesize magnetic carbon-iron nanocomposites using end-of-life cartridge waste toner powder was successfully demonstrated through a single-pot hydrothermal process. The synthesized composite materials' structural, thermal, and magnetic properties were assessed and electrochemical analysis revealed a specific capacitance of 204&#xa0;F/g at a scan rate of 5&#xa0;mV/s. These values are comparable to or exceed those of Carbon/Fe₃O₄-based nanocomposites, suggesting that waste-derived composite materials have the potential to sustainably meet global energy storage demands. Additionally, these composites demonstrated exceptional stability by retaining 83% capacitance for 2000 charge–discharge cycles. The synthesized Fe₃O₄-carbon composite offers several advantages, such as its preparation from waste material and ease of removal through magnetic separation. Moreover, it plays a significant role in reducing electronic waste, serves as a cost-effective approach for electrode material technology, and promotes environmental sustainability by converting waste into valuable energy storage resources. These developments offer opportunities for producing multifunctional composite materials from waste for a wide range of applications.</p>