The synthesis of hyper-cross-linked polymers (HCPs) is typically achieved using costly reagents. This study demonstrates the utilization of a plastic waste, Styrofoam, to create a series of HCPs through a one-pot Friedel−Crafts reaction. The influence of substrate, catalyst, and cross-linker ratio was investigated to yield HCPs with Brunauer−Emmett−Teller (BET) surface areas up to 1199 m2/g. We exploited this recyclate HCP for carbon capture from flue gas, dye removal, and As(V) sequestration from water. The adsorption capabilities of this cost-effective adsorbent were comparable to and surpassed current state-of-the-art nanoporous materials such as metal−organic frameworks (MOFs), activated carbon, zeolites, and other HCPs.