Aluminium 6061 alloy matrix composite materials reinforced with carbon nanotubes (CNTs) and silicon carbide nanoparticles (nSiCs) were prepared by high-energy ball milling and hot pressing. In addition to inducing fine particle strengthening, nSiCs were also used as a solid mixing agent to improve the dispersion of the CNTs in the Al matrix powder. The dependence of the densification and mechanical strength of the composites reinforced with the dual nanoparticles on the milling time is discussed. The crystallite sizes of Al in the composites were also investigated. Moreover, the relative defect ratios of the CNTs in the composites were calculated from the intensities of the D and G peaks of the Raman spectra. With this new approach to composite fabrication, a hardness and tensile strength of 334 HV and 293 MPa, respectively, were achieved. The high-energy ball milling time significantly affected the microstructure and mechanical properties of the composites; however, the dual nanoparticle reinforcement can potentially be used in a variety of industrial component materials with precisely controlled material properties.