Abstract: With the rapid evolution of the new energy industry, developing green, low-cost preparation methods and innovative structures for lithium-ion battery Si/C anode materials has become imperative. Currently, the burgeoning volume of municipal and industrial plastic waste presents tremendous potential for high-value utilization. Driven by global plastic pollution mitigation, integrating industrial circular pathways with technologies for the low-carbon conversion of waste plastics is rapidly emerging. Upgrading waste-plastic-derived carbon products into high-performance Si/C anodes offers significant resource, environmental, and economic benefits. This review systematically explores the structural design of Si/C composites and the application potential of waste-plastic-derived carbon materials. Through advanced thermal conversion, waste plastic can be transformed into high-value carbon nanomaterials, including graphene, carbon nanotubes, carbon nanofibers, and carbon spheres. Concurrently, engineering Si/C composites with core-shell, yolk-shell, porous, embedded, and hollow structures effectively alleviates silicon volume expansion while enhancing electrode conductivity and cycling stability. However, despite recent advances in Si/C anodes, large-scale production still face challenges such as complex synthesis processes, high costs of precursors, and severe interfacial reactions. Moreover, existing reviews predominantly focused on either synthetic strategies for Si/C anodes or the modification effects of single carbon sources; a systematic integration of "waste plastic recycling" with "Si/C anode structural engineering" remains underexplored. To address these gaps, this review comprehensively analyzes the mechanisms, merits, and demerits of major Si/C anode structures (including carbon-coated, embedded, and hollow structures) and discusses the impact of structural design on electrochemical performance. Furthermore, it highlights the technical pathways for converting waste plastics into diverse carbon material frameworks via flash Joule heating, template-assisted pyrolysis, and microwave carbonization, while evaluating their efficacy in Si/C anodes. Ultimately, this review demonstrates the distinct advantages of using waste-plastic-derived carbon to reduce raw material costs and optimize electrochemical performance. Future research directions are proposed, focusing on green, resource-recycling preparation processes, interdisciplinary synergies, and life cycle assessment (LCA) frameworks, aiming to promote the low-carbon development of the energy storage industry and forge a deep integration between the battery economy and the circular economy.