Anaerobic digestion represents a relevant biological technology for the energy recovery of biodegradable waste and for reducing environmental impact, contributing to the transition toward sustainable and circular energy systems. The efficiency of this process is closely correlated with the structure, composition, and diversity of microbial communities involved in the sequential stages of hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Each microbial group plays a specific and essential role: hydrolytic bacteria break down complex polymers into simpler molecules, acidogenic bacteria convert these molecules into volatile fatty acids, acetogenic bacteria produce acetate, hydrogen, and carbon dioxide, and methanogenic archaea finalize the process by generating methane-rich biogas. The present paper examines the relationship between microbial diversity and the energy efficiency of anaerobic digestion, considering and synthesizing data, trends, and conclusions reported in the scientific literature. The main microbial groups involved in the process are analyzed, including hydrolytic and acetogenic bacteria as well as methanogenic archaea, highlighting the biological mechanisms and interactions that influence process stability, energy yield, and system resilience under variable operational conditions. In addition, trends identified in recent studies regarding the impact of microbial diversity on biomass-to-energy conversion and on the reduction of greenhouse gas emissions associated with biodegradable waste management are discussed, emphasizing the importance of microbial community composition for sustainable energy production. The analysis indicates that higher microbial diversity is associated with increased energy efficiency, more stable biogas production, reduced accumulation of intermediate metabolites, and enhanced resilience of the anaerobic digestion process in response to fluctuations in feedstock composition or environmental conditions. In this context, integrating microbial and biological considerations into the design, monitoring, and operation of anaerobic digestion facilities can significantly contribute to optimizing energy performance, improving process reliability, and promoting environmentally sustainable solutions for the management of organic waste. This perspective underscores the central role of microbiology in advancing renewable energy technologies and supporting the broader goals of sustainable development and environmental protection.