Thermoelectric (TE) materials appear to be a potential option for directly converting waste heat from industry, dwelling appliances and infrastructure, automobiles and alternative fuel combustion exhaust converted to electrical energy. When technology is accessible, giving significant cost, significant conversion, reliability, efficiency, and advanced ecological qualities of final products, TE power generation will be in high demand. Organic thermoelectric materials have shown promising and due of their drew a lot of attention large-scale production, significant cost, lightweight, solution-processed manufacturing, and flexible electronics applications over their inorganic counterparts. Furthermore, organic TE materials provide direct energy conversion from the human body with minimal electric consumption. In this chapter, we mainly focus on the organic TE material, which covers the material synthesis process, fundamental doping mechanisms, composite, and their thermoelectric power generator. We hope this chapter will add to our understanding of how organic materials are important in the advancement of organic electronics for new technologies.