Carbon nanotube (CNT) aerogels have gained significant attentions for diverse applications because they formed three-dimensional assemblies of CNTs with high electrical conductivity and large specific surface area, maintaining the intrinsic properties of CNTs. Polymer infiltration is commonly employed to improve the fragility and poor mechanical properties that limit their applications. Nonetheless, the unimpregnated area can easily be created due to the fine and complex impregnating path inside the aerogel. Here, we utilized reactive infiltration of polyamide 6 for fabricating aerogel-based nanocomposites via facile impregnation with ultralow-viscosity monomers, significantly improving the mechanical properties while maintaining the network structure of aerogel. The nanocomposite exhibited an excellent tensile strength of 61.3 MPa, representing a 55.6% improvement over that of pure polymer. By fabricating the novel nanocomposite with a stable interconnected structure, we confirmed one of the highest levels of electrical conductivity among polymeric nanocomposites and also verified the potential applications as heat-dissipation materials.