Organic materials play a pivotal role in modulating the structure and properties of cellulose-based hydrogels (CBHs), emerging as a key strategy to enhance their functional diversity and adaptability across a wide range of applications. The incorporation of polysaccharides, synthetic polymers, and functional organic small molecules facilitates the formation of multi-network structures and interfacial synergies, significantly improving the mechanical strength, environmental stability, and stimuli-responsive behavior of hydrogels. These organic components interact with CBH matrix through hydrogen bonding, covalent bonding, hydrophilic/hydrophobic modulation, and active molecule encapsulation, thereby endowing the CBH system with multifunctional properties such as controlled release, improved biocompatibility, and environmental responsiveness. A deeper understanding of these functional regulation mechanisms not only drives practical advancements in biomedicine, environmental remediation, and intelligent sensing, but also provides essential theoretical insights for green synthesis and multiscale structural design of CBHs. Consequently, organic materials have become indispensable functional elements in the development of high-performance CBH systems.