Embodiments of the present invention provide polymer matrix nanocomposites reinforced with nano-scale materials such as nanoparticles and carbon nanotubes and methods of fabricating. The nanomaterials are provided within relatively low weight fractions, for example in the range of approximately 0.01 to about 0.4% by weight and distributed within the matrix by a magnetic mixing procedure to provide substantially uniform reinforcement of the nanocomposites. Advantageously, these nanocomposites provide significantly enhanced tensile strength, strain to failure, and fracture toughness over corresponding neat matrices.