Thermochemical conversion of plastic waste presents a viable pathway for sustainable hydrogen production, integrating waste reduction with low-carbon energy generation. This review focuses on hydrogen production via pyrolysis and gasification processes, highlighting the technological enhancement, life-cycle performance, and techno-economic feasibility. Conventional pyrolysis primarily targets liquid hydrocarbon recovery; however, recent advances in catalytic and plasma-assisted configurations enable higher hydrogen yields (55–7 vol%) with markedly reduced tar formation. Gasification, particularly when integrated with carbon capture and storage (CCS), offers the most significant potential for emission reduction (to 2–4 kg CO₂ eq kg⁻¹ H₂) and large-scale deployment. Comparative life-cycle and techno-economic analyses indicate that levelised hydrogen costs range from 2.5 to 5.0 USD kg⁻¹ , depending on energy sourcing, integration, and by-product valorisation. Monetisation of carbon-rich co-products such as nanotubes and graphene can further offset production cost by approximately 2 USD kg⁻¹ H₂ under favourable market conditions. Emerging machine-learning and digital-twin frameworks enhance process optimisation and sustainability management, though industrial-scale implementation remains limited. Policy mechanisms, including carbon-credit incentives and extended-producer-responsibility schemes, are essential to enhance financial viability and social acceptance. The practical novelty of this work lies in bridging life-cycle and techno-economic perspectives, offering a unified framework to evaluate both performance and scalability of plastic-to-hydrogen systems.