Efficient strategies (degradation or recycling) for converting multifarious plastic wastes are imperative due to the resulting detriments to the environment and human life. With this in mind, the versatile and sulfur-mediated conversion of plastic wastes into value-added adsorbents is presented. The essential sulfur medium promotes the thermal polycondensation of polymer chains and leads to an impressive carbonization yield of 91%, significantly exceeding the control process without sulfur (0–12%). The final sublimation of sulfur endowed carbon materials with high porosity (SBET up to 888 cm2/g), while the attack of sulfur radicals naturally results in a high sulfur content (8.66–12.08%) of the carbon framework. Interestingly, the polar interactions (CO2 with sulfoxides, sulfones, and sulfonic) ensured the S-doped carbon good performance in CO2 adsorption (up to 4.6 mmol/g at 273 K), while the coordinating role of the sulfide group contributed to the heavy metal adsorption [removal efficiency of 99.5% for Pb(II) and 99.8% for Cd(II)].