The combination of photocatalysis and biomass usage is a promising approach to create valuable chemicals and renewable energy more sustainably. This approach has significant environmental and economic benefits. This chapter begins by discussing the importance of managing waste biomass effectively. It then explores how photocatalysis can convert components of biomass, such as sugars, cellulose, lignin, and glycerol, into useful chemicals. Additionally, it investigates how photocatalysis can be applied to generate energy from carbohydrates, lignin, and glycerol. However, a critical issue is the limited understanding of the mechanisms behind photocatalysis in biomass conversion. As a guiding document, this chapter emphasizes strategies and mechanistic considerations necessary for the practical implementation of sustainable photocatalytic reactions in the context of biomass conversion and energy production.