Complementary tools to classical analytical methods, enzymatic biosensors are widely applied in medical diagnosis due to their high sensitivity, potential selectivity, and their possibility of miniaturization/automation. Among the different protocols of enzyme immobilization, the covalent binding and cross-linking of enzymes ensure the great stability of the developed biosensor. Obtained manually by drop-casting using a specific cross-linker, this immobilization process is not suitable for the specific functionalization of a single electrode out of a microelectrode array. In the present work, we developed a nanohybrid enzymatic biosensor with high sensitivity by a mussel-inspired electro-cross-linking process using a cheap and abundant natural molecule (tannic acid, TA), gold salt, and native enzymes. Based on the use of a cheap natural compound and gold salt, this electro-crosslinking process based on catechol/amine reaction (i) is versatile, likely to be applied on any kind of enzymes, (ii) does not require the synthesis of a specific cross-linker, (ii) give enzymatic biosensors with high and very stable sensitivity over two weeks upon storage at room temperature and (iv) is temporally and spatially controlled, allowing the specific functionalization of a single electrode out of a microelectrode array. Besides the development of microbiosensors, this process can also be used for the design of enzymatic biofuel cells.