One of the crucial reasons for growing interest in supercapacitors and hybrid capacitor devices is increasing demand for efficient energy storage devices. The enhanced performance of these textiles is mainly attributed to the incorporation, as part of their structure, of functionalized nanomaterials that are crucial for producing an improvement in their operation and effectiveness. The objective of the present thorough review paper is to highlight the various aspects demonstrating a great scope for functionalized nanomaterial to be explored in supercapacitors and hybrid capacitor device. After discussing the broader space of energy storage devices, we introduced you to the basic principles of supercapacitors and hybrid capacitors. This, again, is indicative of the absolutely vital role that functionalized nanomaterials play in enhancing these device performance metrics, thus generating a comprehensive understanding for their promotion of this energy storage technology. The introduction further outlines what is to cover, presenting a broad view of the purpose and extent of the review consultation. Later sections focus in crazy detail on the whole world of nanomaterials and how they are used for electrode construction. In this context, a systematic classification of nanomaterials and a comprehensive description of various synthesis approaches to their functionalized forms will be provided as basic information in preparation for the subsequent more detailed presentation on different strategies for modification of electrodes to enhance their performance. Thus, the narrative now moves smoothly to advanced/nanocomposite materials designed for supercapacitors and hybrid capacitor devices. Understanding structural relationships through different types of synthesis and X-ray techniques gives important insight into the complex relationship between material composition and performance properties. It provides a critical assessment of current and future trends in research and development (including breakthroughs, reagents, products, applications, and emerging technologies). In addition, we explain the inherent difficulties faced when incorporating functionalized nanomaterials into more applied use cases and provide a detailed insight on the obstacles that need to be addressed to fully unlock their capabilities.