The catalytic activities of supported metal nanoparticles can be tuned by appropriate design of synthesis strategies. Each step in a catalyst synthesis method can play an important role in preparing the most efficient catalyst. Here we report the careful manipulation of the post-synthetic heat treatment procedure—together with control over the metal loading—to prepare a highly efficient 0.2 wt% Pt/TiO₂ catalyst for the chemoselective hydrogenation of 3-nitrostyrene. For Pt/TiO₂ catalysts with 0.2 and 0.5 wt% loading levels, reduction at 450 °C induces the coverage of TiO_x over Pt nanoparticles through a strong metal–support interaction, which is detrimental to their catalytic activities. However, this can be avoided by following calcination treatment with reduction (both at 450 °C), allowing us to prepare an exceptionally active catalyst. Detailed characterization has revealed that the peripheral sites at the Pt/TiO₂ interface are the most likely active sites for this hydrogenation reaction.