Biobased resins and composites with high biobased carbon content were prepared and characterized. Epoxidized linseed oil (ELO) was copolymerized with four cyclic anhydrides, the initiation step being optimized in terms of initiator nature and its ratio. The optimized ELO/anhydride formulations were combined with a high load of lignin, as biofiller, ~30 wt%. The obtained materials were characterized by TGA, DSC, DMA, gel content, water absorption (WA) and Shore hardness tests. The results revealed very good thermomechanical properties, high gel content and low WA, opening the way to their utilization as a sustainable alternative to oil-based resins and composites.