As a strategy for mitigating climate change and waste problems, waste-to-energy has rapidly emerged. Thermochemical conversion is a widely used waste-to-energy process that involves the degradation of waste structure at high temperatures under oxygenic or anoxygenic atmosphere. Integration of different thermochemical conversion processes enhances the overall efficiency of energy recovery from waste substances. To maximize the enhancement of waste-to-energy efficiency, the selection of thermochemical conversion system configurations is critical. Understanding possible configurations of hybrid thermochemical waste conversion processes (e.g., pyrolysis, gasification, hydrothermal carbonization, and aqueous-phase reforming) is necessary for further development and propagation of the integrated hybrid thermochemical waste conversion processes. To this end, we provide a systematic review of existing hybrid thermochemical waste conversion systems that integrate different thermochemical conversion processes for waste-to-energy. The challenges and future research suggestions regarding integrated thermochemical waste conversion processes are also discussed.