Stem cell-based tissue engineering offers transformative solutions for regenerating damaged tissues, such as bone, cartilage, and neural tissues. Chitosan and cellulose nanoparticles have emerged as promising biomaterials for enhancing stem cell delivery and scaffold performance due to their biocompatibility, biodegradability, and tunable properties. Chitosan, with its antimicrobial and bioadhesive properties, supports stem cell adhesion and differentiation in soft tissue scaffolds. Cellulose nanoparticles, including cellulose nanocrystals (CNCs), nanofibrils (CNFs), and bacterial nanocellulose (BNC), provide mechanical strength for hard tissue regeneration. This review examines their synthesis, properties, and interactions with stem cells, particularly mesenchymal stem cells (MSCs), in tissue engineering applications. A comparative analysis highlights their complementary roles, while challenges like physiological stability and scalability are addressed. Recent advancements, such as 3D bioprinting and growth factor functionalization, enhance their potential. Future research should focus on optimizing stem cell-scaffold interactions and ensuring clinical safety.