<p>Sabatier reaction is an emerging strategy for mitigating anthropogenic CO₂ emissions while producing renewable CH₄, a versatile energy carrier for heating, electricity generation, and hydrogen production. Developing efficient, low-cost catalysts is challenging, particularly in achieving stable, well-dispersed supports with tunable surface chemistry for methanation. Biochar derived from agrowastes offers a sustainable alternative to conventional oxide supports owing to its low cost, high carbon content, tunable micro-mesoporosity, and ability to anchor metal nanoparticles. Herein, we design and evaluate date palm trunk biochar-immobilized mono and bimetallic Ni, Fe, and NiM (M = Fe or K) catalysts for CO₂ methanation. With specific objectives of developing a sustainable supported catalyst by pyrolysis at 500 °C, and evaluating the influence of temperature and pressure on using an industrially relevant H₂/CO₂ ratio of 3. CO₂ methanation performance was assessed in a continuous-flow reactor. The biochar exhibited favorable micro-mesoporous characteristics and high carbon content, enabling effective metal dispersion. Ni loading strongly influenced catalytic performance; the optimal catalyst (0.5 mmol Ni g⁻¹, BCNi-3.0) achieved 58% CO₂ conversion and 91% CH₄ selectivity at 400 °C and 1 bar. Increasing pressure to 30 bar enhanced performance to 76% CO₂ conversion and nearly 99% CH₄ selectivity, with stable operation over 20 h. Bimetallic NiFe catalysts formed NiFe₂O₄ and NiO phases and promoted CO formation via the reverse water gas shift reaction, while K promotion further favored CO production. Overall, biochar-supported Ni-based catalysts demonstrate a sustainable and efficient platform for CO₂ methanation with reduced hydrogen demand.</p>