In this study, platinum (Pt) catalysts for proton exchange membrane fuel cells were manufactured using atomic layer deposition (ALD) to simplify the synthesis process, achieve the formation of uniform nanoparticle, and reduce and enhance the utilization of precious metals. The deposition behavior of Pt nanoparticles was investigated depending on the ALD deposition temperatures. Pt catalysts were synthesized by ALD at 250 °C, 300 °C, and 350 °C, and thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy were employed to investigate the deposition characteristics, Pt nanoparticle distribution, size, and crystal structure of each catalyst. To apply them in fuel cells, the electro-chemical active surface area was determined using cyclic voltammetry, and membrane electrode assembly cells were fabricated to study fuel cell performance. Ultimately, it was revealed that the ALD synthesis of Pt catalyst should be conducted at deposition temperatures below 300 °C, and these Pt catalysts exhibited superior characteristics compared to wet-based Pt catalysts. This study provides fundamental information and direction on the ALD process for synthesizing catalysts when the advanced Pt based catalyst is synthesized by ALD through various approaches.