Polymers are central to our present and future society, enabling improvements in nearly all aspects of daily life. However, our lifestyle also generates significant problems due to the way we use polymers. Most polymers are discarded after use, rarely recycled, and end up in landfills, rivers, and oceans. This fate exemplifies the current linear, fossil-based produce-use-discard value chain, which contributes to enormous environmental pollution. Therefore, a fundamental transition is needed in the field of polymeric materials—from fossil-based feedstock and single-use applications to the continuous reuse of polymeric products. Parallel to recycling efforts, the transition toward bio-derived polymers has gained increasing attention, driven by the urgent need to reduce reliance on finite petroleum resources and mitigate the environmental impact associated with conventional polymer production. Our research focuses on both existing polymers and the design of novel polymeric structures that are more amenable to recycling. The key is incorporating suitable degradable functional groups or smart monomers into polymers during the design stage. Our approach involves the use of various imine, acetal, triazine, and hexahydro-s-triazine derivatives as cleavable groups within the polymer network. Combining advances in chemical recycling strategies with the integration of renewable feedstocks represents a powerful approach to address both the recyclability and sustainability challenges associated with polymers. Most importantly, we demonstrate chemical depolymerization, the subsequent separation and reuse of recovered building blocks, and closed-loop recycling or upcycling of novel polymers. Our studies are expected to contribute to the development of a circular plastic economy and to drive research on environmentally friendly materials forward.