<p>The escalating global energy crisis, exacerbated by an enduring reliance on fossil fuels, necessitates an urgent transition towards cleaner, sustainable energy alternatives. While numerous reviews have addressed the fundamentals of anaerobic digestion (AD), few have critically synthesized recent advancements in pretreatment and co-digestion strategies alongside. This review provides a focused evaluation of how biomass pretreatment and synergistic co-digestion approaches address the complex structure of lignocellulosic feedstocks and process instability. We highlight contradictions in recent findings such as varying efficiency of alkaline pretreatment versus fungal bio-pretreatment and discuss emerging techniques that enhance process robustness. In addition, we analyse the techno-economic feasibility and policy frameworks shaping the scalability of biogas plants, emphasizing the need for integrated approaches that combine process innovation with supportive governance. Current work provides a comprehensive overview of biogas technology, positioning it as a pivotal solution within the global energy landscape. The analysis effectively establishes the context of the global energy crisis and the imperative for renewable energy, offering a detailed exposition of the anaerobic digestion process. It thoroughly addresses both the inherent advantages of biogas and the multifaceted challenges impeding its widespread adoption. This paper identifies critical research gaps and proposes specific, actionable future directions for optimizing biogas production and accelerating its widespread adoption as a sustainable energy solution.</p>