Nanocellulose (NC) is a unique and promising natural material derived from native cellulose. It has attracted much attention for its versatility in construction composites, which have improved chemical and mechanical properties. This review covers the type of biomass used and NC production methods, emphasizing biotechnological routes, which promote their biological properties (biocompatibility, biodegradability and low toxicity), fundamental for medical applications. NC has many hydroxyl groups on its surface, enabling its structure to be modifiable, adaptable and viable for various fields. Furthermore, NC‐based biosensors are suitable for food quality control, monitoring environmental analytes, and particularly in health diagnostics, such as COVID19 detection. The developed analytical devices were described in a table, including information about the sensor molecule, reading system, analyte, range, detection limit, sensitivity and analytical performance.