A polymer nanocomposite was produced by using poly(methyl methacrylate) (PMMA) as the matrix and crystalline Brookite TiO2 nanorods (NRs) as the filler, in loading range between 5 and 30% in weight. The colloidal NRs were synthesized through low temperatures hydrolysis of titanium tetraisopropoxide, and showed a prolate shape with length to diameter aspect ratio around 20. The PMMA/Brookite composites were characterized through atomic force microscopy (AFM) and transmission electron microscopy (TEM) for the morphology, and through differential scanning calorimetry (DSC) and nanoindentation for the thermal and mechanical properties, respectively. It was found that, with respect to the bare PMMA, the glass transition temperature is increased of about 10°C for all the composites, whereas the reduced modulus and hardness are substantially increased only for 10 wt% loading. The TEM analysis showed evidence of NRs aggregation on increase loading.