Abstract Large volumes of polymeric waste, including natural biomass residues and synthetic waste, motivate the development of a general, robust and flexible process for mining the energy and resources contained in these wastes. By analyzing the positive and negative aspects of current, conventional technologies for the recovery of energy from polymeric waste, an integrated concept of a hybrid technology combining biochemical (anaerobic digestion, gas fermentation, carbon chain elongation) and thermochemical conversion processes (pyrolysis, gasification, hydrothermal carbonization) was proposed. The hybrid technology aims at simultaneously enhancing the efficiency and stability of biochemical conversion, controlling the gaseous and aqueous pollution from thermochemical conversion, and sequestering carbon. This paper presents a detailed review of state-of-the-art research relating to the principles, technical feasibility and practices involved in each technical link between the two conversion processes.