Carbon-basedCarbon-based nanocomposites nanocompositesNanocomposites (NCs) are promising electrocatalysisElectrocatalysis for sustainable energy systems due to their high conductivity, stability and cost-effectiveness. This chapter explores the various types of carbon-based NCsCarbon-based NCs such as grapheneGraphene, carbon nanotubesCarbon Nanotube (CNT) (CNTs), carbon quantum dots (CQDs) and amorphous carbon, along with their synthesis methods like chemical vapor deposition (CVD), hydrothermal synthesis, sol–gel processes and electrochemical deposition. These methods offer control over the size, morphology and surface characteristics of the NCs, which are essential for enhancing electrocatalytic performance. These techniques enable precise control over NC properties, enhancing their performance in key reactions such as hydrogen evolutionHydrogen evolution (HER), oxygen evolutionOxygen evolution (OER), and oxygen reductionOxygen reduction (ORR). Carbon-based NCs improve these reactions by offering a conductiveConductive framework that promotes efficient electron transfer, increases the surface area for reactant adsorption and stabilizes the catalysts under harsh conditions. Their excellent electrochemical properties make them ideal for applications in fuel cells, water splitting and metal–air batteries. Furthermore, the chapter discusses the application of carbon-based NCsCarbon-based NCs in supercapacitorsSupercapacitors and solar energySolar energy conversion. These materials provide enhanced reaction kinetics, higher energy storage capacity and improved charge transfer efficiency making them suitable for large-scale renewable energy systems. The chapter ends with an overview on future implementation to optimize the synthesis of carbon-based NCs and further enhance their efficiency and durability for sustainable energy applications.