Metal oxide nanostructures have recently garnered much recognition because of their exceptional electrical, optical and molecular properties that provide a fascinating platform for the development of biosensors. Till recent years, various methods and techniques such as chemical precipitation, electrodeposition and hydrothermal treatment have been utilised to fabricate metal oxide-based biosensors with high sensitivities and low detection limits. However, a number of these fabricated devices are irreversible and have low sensitivities. Therefore, more efficient and reliable biosensing technologies need to be developed. Biosensors are usually defined as an analytical equipment that consists of a biological recognition component integrated to a transducer and signal processing unit that converts, amplifies and displays biochemical activity into a measurable signal. The goal of this bioelectrical combination is to detect pathogenic and physiological molecules in the food or body for the early detection as well as treatment of diseases using the high sensitivity and selectivity of biological sensing. We review here some of the main strategies used in the fabrication of metal oxide nanostructures, including the advancements in biosensors based on metal oxides and evaluate their properties with the aim of motivating greater interest in improving the development of biosensors for medical diagnosis. © 2019, Springer Nature Singapore Pte Ltd 2019.