<p>The global surge in polyvinyl chloride (PVC) waste demands urgent technological solutions that address both environmental persistence and resource recovery. Here, we present a triple-functionalization strategy that converts chlorinated plastic waste into high-performance sodium-ion battery anodes through molecular-level control of carbon architectures. Sequential dichlorination, sulfonation, and N-doping collaboratively reconfigure precursor reactivity, steering pyrolysis toward hierarchically porous hard carbon with tailored defect chemistry. Sulfonic groups stabilize 3D carbon skeletons during carbonization, enabling closed-pore formation with an average diameter of ∼2.55 nm while N-doping expands interlayer spacing (0.382 nm) and creates adsorption-active pyrrolic-N sites. This defect-engineered synergy delivers unprecedented sodium storage metrics: 355 mAh g⁻¹ reversible capacity at 0.1 A g⁻¹ (95.4% of graphite’s Li-ion capacity), a capacity retention of 216 mAh g⁻¹ after 1000 cycles at 1.0 A g⁻¹ (70.1% capacity retention), and 188 mAh g⁻¹ even at a high current density of 5.0 A g⁻¹. <i>Operando</i> analyses reveal a potential-dependent storage hierarchy: surface-dominated adsorption transitions to intercalation/filling-dominated behavior with defect-buffered structural integrity. The process simultaneously achieves 25% carbon yield from PVC and avoids toxic dioxin emissions, establishing a scalable prototype for sustainable energy storage systems.</p>