Carbon nanofibers (CNFs) are fibrous nanostructures of sp2-hybridized carbon having partial structural similarity with carbon nanotubes (CNTs). This chapter reviews the structure, synthesis techniques, properties and applications of CNFs. CNFs can be produced either by vapor phase growth using chemical vapor deposition or by carbonization of pre-synthesized polymer nanofibers. Both techniques offer an easy synthesis of CNFs as compared to that of CNTs. The synthesis techniques affect their structure as well as properties significantly. CNFs, owing to their graphitic structure, offer unique properties such as high mechanical strength, corrosion resistance, thermal and electronic conductivities. In view of their unique properties, CNFs have drawn significant attention toward their use in advanced applications such as electrochemical power generation and storage, high-strength composites, sensors, adsorbents. Promising advancements project CNFs as the futuristic materials for lithium-ion batteries, supercapacitors, fuel cells and solar cells.