Biomass is a promising feedstock to source renewable carbon needed to produce biobased chemicals and materials. Lignocellulosic biorefineries, however, can only be economically viable when all three major biomass components (lignin, cellulose, and hemicellulose) are valorised. Current extraction processes lead to the irreversible degradation of the lignin polymer. Aldehyde assisted fractionation (AAF), which relies on the protection of the native β-O-4 linkage of lignin with an aldehyde, can overcome this challenge. While the uncondensed aldehyde-stabilized lignin can be further depolymerized into its constituting aromatic monomers at near-theoretical yields, hemicellulosic sugars and highly crystalline cellulose polymers can also be efficiently recovered. Beyond stabilization, AAF also enables the production of functionalized building blocks such as dimethylglyoxylate xylose (DMGX), a bioplastic monomer produced from xylose and with similar properties to PET precursors. Due to the complexity of biorefining schemes, the use of process synthesis and optimization tools is required to maximise energy and carbon use while minimizing costs and environmental impacts. The design of a novel integrated biorefinery capable of processing 25% of sustainably available lignocellulosic biomass in Switzerlandis presented in this study, whose aim is to identify the key parameters influencing costs and environmental impact.