Landfill biogas offers a promising opportunity to supply society’s energy requirements, following the waste-to-energy approach, which issuitable for sustainable production. However, structural modification for its utilization is the main gap, requiring additional research efforts. Considering this issue, the current study aims to design an eco-friendly polygeneration method for landfill biogas utilization for a cutting-edge heat recovery system that integrates a cold energy recovery and utilization unit for liquefied natural gas. The liquefied natural gas recovery section, the organic Rankine cycle with a zeotropic mixture, and the Kalina cycle are all started using the flue gas from the combustion of biogas in a cascade process. In addition, the waste heat of the Kalina cycle is recovered by a single-effect desalination cycle and liquefied natural gas recovery section. Also, a water electrolysis process is integrated into the whole system. As a result, the products include hydrogen, electricity, natural gas, hot and cold water, and freshwater. The Aspen HYSYS software is utilized to design the system and investigate its thermodynamic, environmental, and economic aspects. The results demonstrate an energy efficiency of 57.54 % and an exergy efficiency of 18.78 %. Also, the carbon dioxide footprint associated with the system equals 0.34 kg/kWh, and the specific cost of products is 73.96 $/GJ. An optimal exergy efficiency of 25.8 % and a specific cost of products of 69.7 $/GJ are obtained by means of an intelligent optimization approach that ultimately makes use of non-dominated sorting genetic algorithm-II and artificial neural networks.