A detailed computational investigation, based on density functional theory, of the interaction of polyaniline (PANI) and graphene nanoribbons (GNRs) with SrTiO3 is presented. The adsorption of PANI in various oxidation states and co-adsorption with GNRs is found to be thermodynamically favourable. Adsorbed PANI introduces N and C 2p states into the SrTiO3 bandgap, while co-adsorption of PANI and GNRs leads to a bridging of the gap and semi-metallic behaviour, thus rendering the electrical properties highly sensitive to the loading of the GNRs/PANI in the composites. Modelling the lattice dynamics of the composites predicts a 68–88% reduction in the lattice thermal conductivity due to reduced phonon group velocities. Taken together, these findings provide insight into the growing number of experimental studies highlighting the enhanced thermoelectric performance of oxide-polymer composites and indicate co-adsorption with graphene as a facile direction for future research.