The control of the shape and dispersibility of Pt nanoparticles (NPs) supported on Al2O3 is challenging. To address this issue, the use of metal-organic frameworks as a template for the preparation of heterogeneous catalysts is a promising methodology. Herein, we used an Al-based metal-organic framework as a medium to synthesize uniform Pt NPs supported on γ-Al2O3 (Pt@γ-Al2O3) in the absence of protective and capping agents and subjected these nanoparticles to instrumental analyses. Microscopic imaging indicated that nanoparticles had diameters of 2–5 nm (mean = 3.4 nm) and revealed the formation of Pt nanocubes on the alumina surface. Pt@γ-Al2O3 exhibited excellent catalytic activity for propene oxidation and displayed long-term stability, with the corresponding activation energy determined as 63.9 kJ mol−1. Moreover, Pt@γ-Al2O3 also effectively catalyzed the gas-phase hydrogenation of nitrobenzene to aniline at 100 °C, achieving a turnover frequency of 565 h−1 and a selectivity of >90%. Thus, the obtained results contribute to the further development of supported heterogeneous catalysts from metal-organic frameworks as precursors and media.