In recent years, lignin has attracted substantial attention from researchers because of its diverse sources, low cost, and renewability. The effective functionalization and enhanced value‐added utilization of lignin have successfully addressed the challenges associated with biomass resource waste, low utilization rate, high material cost, and underwhelming performance in energy, environmental protection, and medical applications. The emergence of lignin carbon quantum dots (LCQDs) has opened new avenues for the development and utilization of lignin by offering exciting opportunities for their applications. LCQDs possess unique characteristics such as fluorescence properties, size effect, surface effect, and interface effects, which are promising for applications in many fields. This paper provides a comprehensive overview of the structure and applications of lignin with a specific focus on the preparation method of LCQDs as well as their various applications in drug delivery systems, electrode material fabrication, and antibacterial agent development. Furthermore, this study offers valuable insights into the prospects of LCQDs and aims to contribute to their functional development. Finally, the challenges associated with leveraging the fluorescence properties of LCQDs are discussed, along with potential directions for future research.

This study presents a novel structural modification strategy for lignin, utilizing a ternary eutectic solvent system (TESS), which induces targeted derivatization. The resulting lignin-based functional hydrogel (LBFH), prepared via rational cross-linking of derivatized lignin precursors, exhibits exceptional hygroscopic properties, with a water swelling ratio of 934.0%. Water absorption kinetics were subjected to rigorous analysis through the employment of a dual-modeling strategy that incorporates Schott kinetics and Fickian diffusion mechanisms, thereby elucidating the synergistic dynamic processes underlying surface adsorption and matrix penetration. Remarkably, LBFH maintains 48.6% water retention capacity after 7 days atmospheric exposure (25 °C, 60% RH), demonstrating unprecedented environmental stability among biopolymer hydrogels. The engineered properties of LBFH suggest its potential application in sustainable agricultural practices as drought-resistant soil amendments, and in environmental remediation as contaminant-adsorptive matrices.