In polymer nanocomposites, a very large interfacial area between the nanoscale reinforcement and the host matrix is expected to impart unusual properties which are not possible in the conventional composite materials which involves length scales of micrometer to millimeter. Nanocomposites have also been investigated as a matrix-strengthening agent in conventional composites which results in the so-called multi-scale composite material. In this work, we focus on a model nanofiber reinforced polymer multi-scale system to study the effect of nanofibers content, mixing homogeneity, and other parameters on the resultant mechanical properties. To achieve this, we synthesized randomly oriented pristine PAN nanofibers of an average size of 500 nm by electrospinning which were also filled with 20 nm sized TiO2 nanoparticles to make PAN/TiO2 composite nanofibers. The pristine and composite nanofibers were then added as reinforcement in thin films of poly(methylmethacrylate) (PMMA) by solution casting method in 5, 10 and 15 wt. % ratio. The nanofibers and nanocomposites were characterized by scanning electron microscopy and X-ray diffraction. The mechanical behavior was investigated by dynamic mechanical analyzer using strain ramp test in the tensile mode. The strength of the TiO2/PAN/PMMA nanocomposites increased from 8.77±1.15 MPa for 5 wt.% sample to 12.09±1.02 and 15.27±0.28 MPa for 10 and 15 wt.% samples, respectively. The Young’s modulus and strain to failure also increased monotonically with increased in the nanofiber content. The higher interfacial area between the nanofiber and matrix results in enhanced mechanical properties, however, the exact chemical and physical nature of the interface needs to be further investigated to understand the mechanism of increased resistance to mechanical deformation.