Due to escalating power densities in electronics, information, communication, energy storage, aerospace, and automobile technologies, heat dissipation has become immensely essential for the efficient performance and reliability of photonic, electronics, optoelectronics, and other devices in order to proactively prevent premature failure due to overheating. The functionalization and synergistic inclusion of thermally conducting nanoparticles such as carbon derivatives and metallic and ceramic fillers into polymer matrices have resulted in development of thermally conducting polymer nanocomposites. This has enlarged the scope of application of these materials in areas hitherto restricted due to poor thermal conductivity and, therefore, opened broad windows of opportunities for polymer nanocomposites as emerging alternative replacements for metal components in various applications where effective heat dissipation is compulsory for device performance. Thus, this paper critically discusses globally emerging technologies applied in the development of thermally conductive polymer nanocomposites for various industrial applications.