In this paper, an integrated poly-generation process using biogas for the simultaneous production of useful products, including methanol (0.745 kmolMeOh/kmolbiogas), liquid carbon dioxide, CO2, (11.39 m3/h), desalinated water (34.19 m3/h), and heating (23.31 tonLPS/h) is simulated in the Aspen HYSYS software. Due to the feasibility of increasing the methane content of the biogas, the current study is motivated to upgrade the existing biogas stream through a chemical absorption process toward a novel poly-generation model. Hence, an innovative heat integration is arranged, where the arranged system is made of a chemical absorption unit, a biomethane reforming unit, an integrated CO2 compression unit, an ammonia Rankine cycle, a modified organic Rankine cycle, an integrated synthesis gas compression unit, a methanol synthesis unit, and a water desalination unit. The arranged model is analyzed from the 4E perspective (energy, exergy, economic, and environmental), and a comprehensive parametric study is also done. It is demonstrated that the energy and exergy efficiencies of the newly designed model are found as 54.79%, and 61.54%, respectively. In addition, the exergy analysis shows that the total exergy destruction rate equals 74795 kW, to which the biomethane reforming unit has the largest contribution (40%). The CO2 emission intensity corresponding to the model is also calculated to be 1.33 kgCO2/kgMeOh, which is lower compared to that of coal-to-methanol and steam methane reforming methods. Besides, the total annual cost and total product cost of the model are 166732539 $/year and 0.78 $/kgMeOh, respectively. According to the parametric study, methanol production and overall energy efficiency enhance with increasing the gases recycled to the methanol synthesis reactor and the methanol production cost reduces.