With the ever-growing desire for sustainable energy sources, the technology of piezoelectricity has gained increased attention, offering a simple and economical solution for harvesting reasonable amounts of wasted ubiquitous vibration-based mechanical energy into useful electrical energy. Over the past decade, acquisition of nano-scale energy has become a topical subject which has paved its way for the development of piezoelectric nanogenerators (PENGs). These PENGs find their usage in powering micro- to nano-watt scale flexible electronics and can provide wireless data transmission facilities. In addition, the PENGs can also be employed as self-powered biomechanical sensors, which when attached to human body can convert wasted energy from menial regular functions such as walking, muscle stretching, eye blinking, heart beating, and blood flow into electrical energy. The biomechanical sensors are thus able to provide autonomous physiological positioning, remote patient health monitoring and other useful diagnostic information. In this study, nanocomposite-based PENGs were fabricated by dispersing various piezoelectric nanoparticles (BaTiO3, ZnO and PZT) along with graphene nanopowder into a silicone rubber matrix. Based on the acquired results, it was noticed that PZT-based composites showed superior performance in comparison to other ceramics, and graphene had aided in significantly enhancing the performance of the NGs. Moreover, in order to demonstrate the practical application of the developed PENGs, a fully functioning sports shoe-insole nanogenerator was made, where a high voltage of +30.4 V was acquired only during simple walking. The current research had also aimed at proposing a facile and inexpensive method for developing efficient, skin friendly, robust, and highly stretchable bio-motion piezoelectric strain sensors. The developed sensors were studied under various human motions where they responded fairly to almost every movement.