The intensifying global demand for renewable energy and sustainable waste management solutions has elevated anaerobic digestion technology as a critical pathway for converting agricultural residues into valuable biogas. Among the numerous operational parameters governing this complex biological process, temperature and pH stand out as paramount factors influencing microbial consortium activity, substrate degradation kinetics, and ultimate methane yield. This comprehensive research presents an expanded analytical framework based on experimental evidence from agro-waste co-digestion systems, meticulously examining the synergistic effects of temperature and pH on biogas production efficiency. Through controlled laboratory digestion of regionally relevant substrates—including pig dung, goat dung, cassava peels, and vegetable wastes—this study synthesizes microbial population dynamics, physicochemical parameter evolution, and biogas production patterns over a 21-day retention period. The findings robustly confirm that mesophilic temperature ranges (35-37°C) and near-neutral pH conditions (6.8-7.5) substantially enhance both biogas production rates and cumulative yields by fostering optimal conditions for methanogenic archaea. Furthermore, the research highlights the critical role of strategic co-digestion in balancing carbon–nitrogen ratios, improving system buffering capacity, and stabilizing the digestion process against environmental fluctuations. These results contribute significantly to the growing body of knowledge surrounding appropriate, low-cost, and scalable biogas technologies for developing economies, emphasizing the practical importance of optimized environmental conditions for sustainable energy recovery from abundant agricultural residues. The study concludes with evidence-based recommendations for small-scale digesters in tropical climates and identifies promising directions for future research in this vital field of renewable energy.