Carbon-nanotube (CNT) composites have attracted a lot of attention because of their potential applications in many fields. Here, recent advances in the synthesis of CNT composites using supercritical fluids (SCFs) are highlighted. SCFs exhibit unique features for the synthesis of composites because of their unusual properties, such as low viscosity, high diffusivity, near-zero surface tension, and tunability. Preliminary studies show that SCFs show unusual advantages for the synthesis of CNT composites. The morphologies and structures of the resultant CNT composites can be tuned by changing the solvent properties. The SCIF methods not only provide a green route for the synthesis of composites, but also result in nanostructures that have not yet been produced by conventional methods. Moreover, the potential applications of the resultant CNT composites are also discussed.