In this work, we investigate the influence of low temperature reduction conditions (873 K) by different oxygen buffers on the off-stoichiometry of polycrystalline V2O3 thin films. Vanadium oxide thin films (thickness 300 nm and 100 nm) have been grown by reactive sputtering and have been annealed in a buffered atmosphere subsequently. Buffer couples were chosen throughout the stability range of V2−yO3 (y ≤ 0.03) by the use of different oxygen buffer combinations, namely Ni/NiO, Fe/Fe3O4, Cr/Cr2O3 and Mn/MnO. Thin films have been characterized by scanning electron microscopy, X-ray diffractometry and low temperature electrical transport measurements. Upon decreasing the oxygen partial pressure, the mean grain size of V2O3 decreases systematically from 45 ± 20 nm with a high porosity to 27 ± 10 nm without porosity. The most favourable reduction conditions have been identified for Fe- and Cr-based couples. Moreover, all thin films reduced by the four buffer couples exhibit high insulator-to-metal transition temperatures (110–155 K) close to the value of ideally stoichiometric V2−yO3 (y < 0.005) (155 K) as well as large changes in resistance at the transition (three to five orders of magnitude). This oxygen buffer method hence provides a valuable synthesis method of highly stoichiometric polycrystalline V2O3 thin films with technological relevance.