Aramid nanofibers (ANFs) are at the forefront of emerging nanomaterials and are recognized for their outstanding properties, including high tensile strength, high modulus, and excellent thermal and chemical stability. These advantages have paved the way for a wide range of applications in composites, energy systems, protective fields, adsorption processes, and even innovative biomedical products. Despite the growing interest in functional ANF-based composites and their applications in advanced fields, there is still a lack of comprehensive reviews addressing recent fundamental and applied developments. This review aims to provide an up-to-date overview of aramid nanofibers. First, the structure and classification of aramid fibers (para-, meta-, and co-para-aramid) are introduced. Subsequently, the main fabrication methods for aramid nanofibers, including mechanical disintegration, polymerization-induced self-assembly, chemical/mechanochemical deprotonation, and electrospinning, are comparatively reviewed. The importance of post-processing treatments, particularly the removal of residual salts and thermal post-treatments such as hot pressing and thermal annealing, in enhancing the integrity, crystallinity, and thermo-mechanical durability of nanofibrous layers is examined. Furthermore, the distinctive characteristics of ANF-based composites, especially in relation to specific applications, are carefully analyzed. Finally, key challenges such as improving interfacial bonding, long-term stability, scalability, and reducing the environmental impact of processing methods, along with the need for standardized characterization techniques, are highlighted as future directions to facilitate the transition of this technology from laboratory-scale research to industrial applications.