This work focuses on analyzing the physical composition of municipal solid waste (MSW) and the physicochemical characterization of the organic fraction of municipal solid waste (OFMSW) in a city in Northeast Mexico to propose an adequate treatment and valorization system. Diverse samples were analyzed over 5 months at the city of Saltillo landfill, where the daily discarded MSW was classified into household (HW), central market waste (CMW), and public areas and parks waste (PPW). For the HW and CMW, the fraction with the highest proportion was the organic residues from food products, with 22.15 and 25.78%, followed by other organic wastes (manure, yard waste, leaves, etc.) at 12.58 and 10.24%, respectively. Furthermore, the organic fraction was segregated from the rest of the MSW and classified into four subtypes, and their physical composition and physicochemical characteristics were determined. The results contribute to laying the foundations for the proper treatment of the OFMSW not just in the studied region but also in cities with similar conditions. Moreover, the OFMSW’s feasibility in treating via bioenergy technologies is revealed, and this research proposes a biorefinery treatment pathway through dark fermentation followed by high solids anaerobic digestion generating bioenergy and diverse bioproducts.