The interaction between metal and support is known to substantially enhance catalytic activity. Herein, we investigate the effect of the support's oxidation state on the metal-support interaction (MSI) with twodimensional Pt/TiOx catalysts. Using titanium oxide supports with five different oxidation states and Pt nanoparticles deposited on the supports via arc plasma deposition, we accurately performed the CO oxidation reaction in a batch reactor. We confirmed that the catalyst whose support has the highest oxidation state exhibits the best catalytic activity. The catalysts' turnover frequency value varied sequentially from 4.0 to 19.4 at 513 K, and the activation energy also varied sequentially from 23.90 to 19.13 kcal/mol depending on the oxidation states of the supports. Kinetic studies have shown that the additional reaction pathway following the Mars-van Krevelen mechanism formed at the metal-oxide interface, which was affected by the oxidation states of the supports. The compositional effects of the support were confirmed by X-ray photoelectron spectroscopy analysis: the MSI effect was maintained even after the surface of the titanium oxides completely oxidized.