CelluloseCellulose is a biopolymer that is abundant, biodegradable, and renewable. Cellulose is a preferred material in biosensor development due to its properties such as biocompatibilityBiocompatibility, chemical structure versatility, and mechanical durability. When cellulose and nanocelluloseNano-Cellulose (NC) are included in sensor modification, the sensitivity, selectivity, and environmental friendliness of the sensor are enhanced, thereby improving its overall performance. Cellulose-modified sensors are widely used in many areas such as health, environmental monitoring, and food safety. Cellulose-modified biosensors benefit from the material’s capacity to immobilize biomolecules, including enzymes, antibodies, and nucleic acids, thus enhancing biosensor performance through improved molecular recognition, catalytic activity, and signal transduction. The two basic forms of nanocelluloseNano-Cellulose (NC), celluloseCellulose nanofibrils (long and thin cellulose derivatives)Cellulose derivatives and nanocrystals (shorter and more regular cellulose particles), have unique properties such as larger surface area, greater possibilities for chemical and physical interactions, higher aspect ratio, and improved mechanical and optical properties. Cellulose-modified sensors are effective in detecting substances such as pathogens, toxins, and environmental contaminants. Furthermore, cellulose’s inherent biodegradabilityBiodegradability and low toxicity enable the design of disposable and environmentally friendly sensor devices, addressing the growing demand for sustainableSustainable materials solutions in biosensing. This paper synthesizes the latest progress in cellulose-modified biosensors, discussing fabrication strategies, sensing mechanisms, and integration with nanomaterials, as well as emerging applications in point-of-care diagnostics and wearable sensors. The exploration of cellulose-based materials in biosensing not only contributes to the development of sensitive and selective detection tools but also promotes sustainableSustainable materials and scalable approaches for rapid, portable biomolecular analysis in real-world settings.