Abstract: To tackle the high steam demand, heavy fossil fuel consumption and high carbon emissions in heavy oil thermal recovery, research progress in concentrated solar energy–biomass–natural gas synergistic thermochemical hydrogen production and carbon management systems is reviewed. Guided by the cascade energy utilization principle, it first introduces the thermodynamic analysis framework for multi-energy complementary systems targeting the coordinated demand for a steam, hydrogen and CO₂ in heavy oil thermal recovery. It then summarizes solar-driven thermochemical conversion, biomass gasification/pyrolysis, natural gas reforming and their coupling configurations, which are mainly divided into series and cyclic modes: the former upgrades syngas via gasification/pyrolysis-reforming coupling, while the latter combines energy storage with carbon capture through metal oxide redox cycles. Representative studies show that solar-driven biomass gasification achieves a primary energy efficiency of 44.63% and a solar fraction of 29.59%; lab-scale chemical looping units reach 82.5%–96.0% CO₂ capture efficiency; oxy-fuel combustion flue gas can be enriched into dry CO₂ stream after cooling and dehydration, with its composition affected by multiple operating factors. These data reflect performance levels under specific conditions and are not for direct cross-route comparison. Overall, the system hinges on rational matching of solar heat, biomass and natural gas in reaction driving, load regulation and carbon flow organization, as well as cascade integration across unit processes. Future work should focus on high-efficiency reactors, thermal storage and off-design regulation, in-situ separation, chemical looping integration, and scenario-specific system evaluation for heavy oil thermal recovery.