Over the last few decades, the global increase in energy demand and overemission of CO2 urges the researchers to fulfil the current energy demand from fossil fuels to alternative green fuels. In this context, advance energy processes are developed for catalysis using the light energy, electrical energy, and combination of both photo and electrical energy in challenging the present energy crisis. Catalysts at nanoscale incorporated in polymeric matrix have gained much attention due to their versatile and controlled optoelectric properties for their high efficiency in energy evolution even at lower concentrations. The tendency of nanoparticles to show unique properties at each nano-size level leaves a major part of this field either underexplored or unexplored. Their performances can be enhanced by tuning the shape, size, concentration, and combination of different nanocatalysts in different polymers to achieve efficient materials in energy generation industries. This review focuses on the detailed research activities conducted for fabrication of such polymer nanocomposites, properties, and their use in energy application areas. A review for the better understanding of behavior and properties of polymer nanocomposites required in green energy field will help to wisely choose more durable, efficient, and cost-effective polymer-nanocatalyst combination in an organized manner to enhance the efficiency of polymer nanocomposites.