Unique negative giant magnetoresistance (GMR) of up to -43% at room temperature was observed in the 10 wt% titania/polyaniline (TiO2/PANI) nanocomposites prepared by simple oxidation polymerization. And the negative MR value was further evaluated using forward interference model. Other properties were tested and comparatively reported. The resistivity of TiO2/PANI nanocomposites decreased with increasing temperature, indicating a semiconductor behavior. The Mott variable range hopping (VRH) approach indicated that TiO2/PANI nanocomposites are disordered systems in the 3-dimensional VRH regime. The scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) were also used to study morphology, chemical and crystal structure of the nanocomposites. The thermogravimetric analysis (TGA) was used to study the thermal stability of the TiO2/PANI nanocomposites.