The sustainable production of bioenergy has become a vital focus now a days, owing to the heavy demand for renewable energy sources and the urgent need to minimize emissions of greenhouse gases. This chapter explored the usage of agricultural residues, wastewater, and biomass for bioenergy resource recovery through the implementation of biorefinery technologies. The objective is to extract valuable energy resources while minimizing waste generation and having the least possible impact on the environment. To establish a solid foundation, this chapter reviews the current research literature, and relevant standard methodologies within the fields of bioenergy and biorefinery. It highlights the importance of transitioning from traditional fossil fuel-based energy sources to renewable alternatives, discussing the advantages and challenges associated with bioenergy production and emphasize the potential of agricultural residues, wastewater, and biomass as valuable feedstocks for biorefineries. Agricultural residues, including crop residues, animal waste, food-processing byproducts and food wastes, represent a significant resource for bioenergy production, which are abundantly available and can be efficiently converted into various forms of bioenergy through processes, like anaerobic digestion (AD), pyrolysis, and gasification. On the other hand, wastewater is another under-utilized resource, holds great promise for bioenergy generation, where organic contaminants can also be transformed into valuable biogas or biofuels through anaerobic digestion or fermentation approaches. This chapter also delves into the technical aspects and potential limitations of each conversion method, highlighting the importance of optimizing the process parameters for maximum energy recovery.