The increased demand for wearable devices and sustainable energy has stimulated interest in flexible thermoelectric (TE) devices, driving innovation in this field. While wearable devices integrate us into the Internet of Things (IoT), they rely on finite-lifetime batteries. Consequently, there's a need for an alternative energy source to replace battery-dependent IoT devices. A thermoelectric device based on the principle of the Seebeck effect can directly convert temperature differences into electrical energy, and hence it is a potential technology for sustainable waste heat recovery applications. A flexible thermoelectric (TE) device is the top candidate for IoTs applications, which can convert heat radiated from a human body into useful electricity without creating any hazardous by-product. This makes TE technology a green and sustainable energy source with significant potential. The thermoelectric performance of materials is defined by the dimensionless figure of merit, ZT = α2σT/k, where α is the Seebeck coefficient, σ is the electrical conductivity, k is the total thermal conductivity, and T is the absolute temperature. We have developed a flexible thermoelectric film composed of polymer and inorganic composites for wearable thermoelectric devices and its potential impact on wearable technology and sustainable energy solutions will be presented in detail.