The need for flexible sensors arises from the fact their working performances are much better than their rigid counterparts. A range of flexible sensors has been developed by scientists in research labs and industries with varied fabrication techniques and processing materials. The nanomaterials and polymers used to form these sensors have enhanced electrical, mechanical and thermal characteristics. The biocompatible nature of carbon allotropes has also been popularized to devise prototypes for medical purposes. Among the fabrication techniques, the printing methods have been stressed upon due to their low cost and capability for high roll-to-roll production. These flexible differ in their physiochemical forms and operates on a specific or a combination of working mechanisms for the chosen application. This chapter explains the significance of flexible sensors by showing the techniques used to develop them, the associated raw materials and the application of these sensors. It shows the variance in some of the significant fabrication techniques used to develop the flexible sensors.