The synthesis of lignin into lignin nanoparticles (LNPs) is an approach for facilitating new excellent properties, including great specificity, rich functional groups, solubility, and compatibility, for further application in biocomposite systems. There are two types of LNP preparation techniques: top-down (grinding/mechanical milling, chemical etching, sputtering, laser ablation, and electroexplosion) and bottom-up (spinning, template support synthesis, plasma/flame spraying synthesis, laser pyrolysis, chemical vapor deposition, and atomic/molecular condensation) methods. Successful LNP synthesis results in a variety of morphologies, including quasi-spherical, hollow, smooth colloidal, and spherical. The incorporation of LNPs into adhesives has the potential to modify the physical, mechanical, and thermal characteristics of biocomposites. These qualities may include decreased water content, resistance to water absorption, greater tensile and flexural strength, enhanced thermal stability, and nonflammability. This chapter provides insight into the use of LNPs as adhesives for biocomposites, the methods used to synthesize LNPs, the properties of LNPs in combination with some advanced relevant equipment, and the improved characteristics of biocomposites achieved by introducing LNPs to bioadhesives. Knowledge of the characteristics of LNPs will influence the biocompatibility between LNPs and bioadhesives. Thus, by addressing these issues, the future outlook of LNPs can be optimized and widened for other fields.