TiO2 (TiO2) nanomaterials such as nanotubes, nanobelts and nanowires, or fibres possess the superhydrophilicity and capillary activity for constructing sensor/biosensor platforms due to their large surface area, special structural and functional characteristics. Moreover, they exhibit additional features mainly nontoxic, abundance and affordable nature. These properties provided path for numerous applications that includes energy storage, photovoltaics, pharmaceuticals, gas sensors, biosensors, and immunosensors. The hybrid TiO2 nanomaterials with carbon and metal doping showed progress in electrochemical detection of different analytes with and without enzymatic activity. The detection analytes include glucose, organophosphorus pesticides, pharmaceutical drugs, proteins and various biomarkers. This book chapter elaborates the recent advances and role of TiO2 nanomaterials, synthesis procedures, detection mechanisms of environmental toxicants mainly gas sensors i.e., volatile organic compounds (VOCs) and health care biomarkers. The last section discusses the prospects and problems for the use of TiO2 nanomaterials in the future as well as the several initiatives being taken to improve their performance for sensing/biosensing applications.