The rapid expansion of the global population and technological advancements have heightened the need for efficient energy conversion and electrochemical energy storage. Electrochemical energy systems like batteries and supercapacitors have seen notable developments to meet this demand. However, conventional polymeric membrane separators in these systems face challenges due to limited porosity and poor mechanical and thermal properties, reducing overall electrochemical performance. Researchers have incorporated nanoparticles into the polymer matrix to address these limitations and enhance separator properties. Carbon-based nanomaterials, in particular, have gained prominence due to their unique features, such as surface-dependent characteristics, size, porosity, morphology, and electrical conductivity. These properties make carbon-based nanomaterials advantageous in improving energy storage compared to conventional materials. Advanced carbon-doped polymeric membrane separators have emerged as a potential solution to the issues faced by conventional separators. Adding carbon nanoparticles, such as graphene-based materials and carbon nanotubes to the polymeric separators of batteries and supercapacitors has helped researchers solve problems and improve electrochemical performance. This review article provides a state-of-the-art overview of carbon-doped polymeric membrane separators, their properties, fabrication processes, and performance in lithium batteries, as well as supercapacitors. It emphasizes advantages of these novel separator materials and suggests future research directions in this field.