A simple method was used to synthesize the polyaniline nanofiber-coated polystyrene/graphene oxide (PANI-PS/GO) core shell composite using a solution mixing process. GO could be easily coated on PANI-coated PS to form a PANI-PS/GO core shell structure through the ring-opening reaction of the epoxide groups in the GO sheets with amine groups in the PANI nanofibers. The existence of PANI in the PS and PS/GO core shell composite was confirmed by the appearance of a new peak in the photoelectron spectroscopy and energy-dispersive X-ray spectroscopy results assigned to the nitrogen band. Thermal investigation showed that the addition of GO to the PANI-coated PS increased the glass transition temperature of the PANI-PS/GO composites. The thermal stability of the composites was also improved compared to that of neat PS. Electrical conductivity investigation using a four-probe resistivity measurement system showed that PANI addition to the composite not only enhanced the interfacial interaction but also improved the electrical conductivity of the composite. The increased electrical conductivity of the final composite may enable potential electronic applications.