<p>Shell residues from seafood processing and aquaculture industries encounter significant challenges in waste management. There are many traditional and emerging applications of shell waste, but their enormous scale of production outpaces the utilization. This work reports the comprehensive utilization of shell waste by sequentially converting their major components into value-added products by selective chemical transformations. The pigments were extracted using γ-valerolactone (GVL), a biorenewable solvent produced from carbohydrate-derived levulinic acid (LA). The protein component was separated from shells under hydrothermal conditions with or without using any inorganic base. The calcite component was then reacted with LA and formic acid to form calcium levulinate and calcium formate, promising dietary supplements and chemical feedstock. Finally, chitin was converted into LA (30 mol%) under optimized conditions (150 °C, 4&#xa0;h). Separation and value-addition of the components of crustacean exoskeletons demonstrated in this work are scalable, the products are marketable, and the catalyst used is recyclable. LA produced from chitin is used as the reagent and for synthesizing GVL for a closed-loop biorefinery.</p> Graphical abstract <p></p>