Agro-industrial waste is one of the most abundant, renewable, and low-cost biomass, which is mainly composed of lignocellulose. In addition to this, these biomasses are a rich source of bioactive compounds and are widely used for the production of high-value products. Further utilization of these biomasses reduces environmental contamination, ecological damage, and other hazards associated with it. Compared to chemical treatment methods, which require harsh operating conditions and toxic chemicals, biological treatment is a promising technology with low-cost and environmentally friendly processes. These agro-industrial wastes are mainly produced from different industries, either in the form of solid or liquid. In this context, the present chapter has highlighted the utilization of various agro-industrial wastes for the production of various value-added products like biogas, biofuel, compost, biomolecules, and biomaterials. The use of agro-industrial wastes as raw materials can make the agro-industries more sustainable.