Lignin is the most abundant aromatic natural compound and has become a promising material in replacing petroleum-based polymers and introducing advanced materials to wood adhesives. This chapter provides an up-to-date overview of the lignin modifications reported in recent years to synthesize lignin-based wood adhesives. These modifications consist of answers to the challenges faced in the utilization of lignin with different treatments and conditions to prepare versatile lignin-based materials. This chapter focuses on the various aspects of lignin-based wood adhesives such as the introduction of lignin to synthetic polymers, advanced routes of chemical modification, and applications of lignin-based adhesives. The use of lignin to replace formaldehyde-based adhesives is expected to mitigate climate change and contribute to the development of bio-based adhesives for greener wood-based materials in the future.