Recent research has employed porous nano metal oxides (MOs) to store electrochemical energy. Some researchers have been interested in dual and ternary MOs, and more complicated metal oxide composite materials utilized in supercapacitors. This review discusses the electrochemical capacitive efficiency of metallic nanostructures doped in nickel oxide (NiO), methodologies, charge storage mechanisms, and recent research articles because of its better thermal stability, good chemical stability, cost-effective materials, superior theoretical morals of specific capacitance, natural richness, and environmental friendliness. The numerous different metals-doped NiO and their composite oxides have demonstrated good structural strength, reversible capacity, and extensive cycle lifetime. Researchers have indeed investigated nanostructured electrode materials for electrochemical supercapacitor applications.