Additive manufacturing, particularly vat photopolymerization, has emerged as a promising method for fabricating intricate, high-resolution structures with minimal waste. However, concerns regarding the sustainability of vat photopolymerization resins emphasize the need for incorporating biomaterials into these techniques. Lignin, the second most abundant biopolymer and a large-scale industrial byproduct, presents a sustainable alternative to petrochemical-based resins for vat photopolymerization. Despite its potential, lignin’s strong UV absorption, which disrupts photoinitiator activation, has restricted its use in high-resolution vat photopolymerization processes. This study addresses these challenges by developing resins with high lignin content up to 40 wt.% for digital light processing (DLP). Organosolv lignin is acetylated and subjected to an optimized, low-energy UV decolorization process, reducing UV absorption by 71 %. The decolorized lignin is incorporated into bio-based tetrahydrofurfuryl acrylate, enabling high-resolution additive manufacturing with a resolution of 250 µm. The resulting resins exhibit significant mechanical improvements, with stiffness and strength increasing by factors of 15 and 2.3, respectively, demonstrating lignin’s reinforcing effect. This work highlights the potential of high lignin-content resins for sustainable vat photopolymerization additive manufacturing. It provides a pathway to repurpose lignin waste into high-resolution, high-performance, and environmentally friendly materials, promoting the sustainability of additive manufacturing technologies.