Desire to integrate electronic devices more closely into the everyday life of the consumer led to the emergence of flexible devices, which can conform to any shape surface. These flexible devices are lighter, thinner, and more resilient than their rigid counterparts. Since consumers these days are heavily concerned about the visual look of any product along with its technological features, the flexible devices also pave the way for innovation and creativity from the aesthetic point of view. As more and more electronics including wearable devices and displays are shifting towards the flexible regime, their basic components like sensors and integrated circuits are also required to be flexible and conformal. This paper reviews the development and evolution of several types of flexible MEMS sensors, accelerometers, and energy harvesters from the design, fabrication, and performance perspective.