Based on the unique properties, nanostructured ZnO could provide a stable immobilization for biomolecules retaining their biological activity. It has been recently developed as a nice candidate for the construction of biosensors with enhanced analytical performance. In this paper, we reviewed the progress in adapting nanostructured ZnO for several predominantly in biosensing applications based on enzymic reaction, immunoreaction, and molecular compitation. We also described several important considerations when working with nanostructured ZnO mainly centered on the fabrications of ZnO and appropriate strategies for biosensor construction (e.g. modified electrodes and multilayered immobilization).