<p>To mitigate tar-induced efficiency losses in biomass gasification, this study pioneers the application of low-cost laterite nickel ore simulator (Fe₂O₃-MgO-NiO composite catalyst) for catalytic gasification of tobacco stalks in a lab-scale fixed bed. Systematic investigation of catalyst-to-feedstock mass ratio (0.1–0.25), oxygen molar concentration (20%–35%), and H₂O/O₂ molar ratio (0.78–3.12) has been conducted. (1) This article briefly introduces the catalyst and its optimal ratio, highlighting the key achievements: tar reduction of 12.4% and conversion of polycyclic aromatic hydrocarbons (PAHs) of 98.42%. (2) Syngas regulation and hydrogen enrichment: the effects of O₂ and H₂O/O₂ on H₂/CO ratio and H₂ yield are shown, separating the conditions for maximum H₂ enrichment (25%–30% O₂, molar concentration) from those for maximum H₂/CO molar ratio (H₂O/O₂=1.56). (3) Catalyst stability and biochar enhancement: the O₂-TPO findings on carbon deposition resistance and the concurrent improvement in biochar porosity are summarized. O₂-TPO analysis identifies graphitized carbon deposition (650°C–750°C) minimized at 0.1 ratio through MgO-stabilized lattice oxygen (Fe-O-Mg), reducing carbon by 57% versus commercial Ni/Al₂O₃. We have identified that MgO stabilizes Fe-O bonds, forming Fe-O-Mg interfaces that enhance lattice oxygen mobility and reduce graphitized carbon deposition (650°C–750°C), a phenomenon not systematically reported in previous laterite-based studies. The catalyst concurrently enhances biochar porosity, increasing specific surface area by 97% (89.478 m²/g) with 70.4% micropores (2.3 times that of non-catalytic baseline), significantly improving gas-solid mass transfer. Our study provides a holistic view of product distribution (gas, tar, char) under varying catalytic and atmospheric conditions. This work validates laterite nickel ore as an effective “waste-treating-waste” catalyst for integrated in-situ tar removal and hydrogen-enriched gasification.</p>