Electrochemical energy storage devices play a crucial role because of the intermittent nature of renewable sources to the end user from the point of generation for the construction of sustainable energy storage systems. Also, the main crucial factor for the long-life cycle is to optimize the energy and power densitiesPower density of electrochemical energy storage devices, in addition, to meeting the demand for next-generation electronic applications. To augment the overall performance of electrochemical energy storage devices, greater efforts were made devoted toward the search for new materials. Although more research is going on in this field, their performance has not met up with the commercialization level. Further, the development of new electrode materials and the understanding of the mechanism of charge storage required are essential, the focus of the current book chapter reveals the recent progress in polymer-based hybrid nanostructures for supercapacitor applicationsSupercapacitor applications. The various types of conducting polymersConducting polymers, polyaniline, polypyrrolePolypyrrole (PPy), polythiophenePolythiophene (PTh) and poly(3,4-ethylenedioxythiophenePoly(3,4-ethylenedioxythiophene)), as well as their composites with carbon-based materials and metal oxidesMetal oxides and sulfides involved in the performance of the supercapacitor are well documented in detail. We have also demonstrated the recent advancements in hyper cross-linked polymer research and their electrochemical performanceElectrochemical performance studies. Finally, we have summarized the possible challenges and future developments in this research field.