Biomass pretreatment processes using organic solvents have historically been investigated for the separation of lignin from lignocellulosic biomass. This research explores how the pretreatment process can be expanded to fractionate all biomass components from various feedstock and waste streams and transform them into valuable bio-based molecules using green solvent mixtures and mild conditions. Using experimental and computational investigation techniques, this study further expands on the use of the green solvent γ-valerolactone (GVL) in biomass fractionation processes. Combining both results, a complete biodiverse process for the fractionation of all biopolymers in lignocellulosic biomass was achieved. This process yields lignin in native quality, very high purity and very high yield after a single extraction cycle at very mild conditions. Additionally, lignin-free cellulose in very high purity and yield, and hemicellulose degradation products in very high yield and purity, mainly xylose and glucose, can be separated during the process. These properties are essential for efficient valorization of the biopolymer products. The fractionation process proved to be similarly efficient in every step for different biomasses and waste-stream biomasses. GVL could be recovered and reused in every separation step and even be prepared from hemicellulose products, enabling a sustainable biomass dissolution cycle. This cycle stands as a basis for producing valuable biopolymer molecules, from biodiverse origin, that can be further converted into quality products for the chemical industry.