A novel rotary-type atomic layer deposition (ALD) process for coating platinum thin film on three-dimensional (3D) substrates is demonstrated. High uniformity and conformability of the platinum thin-film deposition on 3D substrates were confirmed, ensuring the controllability of the new ALD technique. The results for this technique surpassed those of the conventional wet method and ordinary atomic layer deposition, which both have a limited specific surface area. To demonstrate the application of this new technology, Pt nano-film coated γ-Al2O3 was produced using the rotary-type ALD and applied to diesel oxidation catalysts (DOCs). The produced DOCs showed high Pt content when the number of ALD cycles was increased, and thereby exhibited more complete combustion of gaseous pollutants, such as CO, C3H8, and NO, even at lower temperatures. Pt nano-film deposition by the rotary-type ALD process was first optimised on Si wafer substrates. The process was controlled by four parameters: processing temperature, number of ALD cycles, precursor pulse time, and reactant pulse time. Deposition of the Pt nano-film was mainly determined by the processing temperature and the number of ALD cycles. The average growth per cycle and density of the Pt nano-film were found to be 0.8 Å/cycle and 21.0 g/cm3, respectively. The same procedure and conditions were applied to 3D γ-Al2O3 powder substrates for DOCs, which demonstrated greater conversion performance compared with conventional Pt-used DOCs.