Reducing platinum (Pt) usage in the polymer electrolyte fuel cells (PEFCs) has become one of the main issues in the global commercialization of PEFCs. In this work, we describe a facile and scalable method to deposit Pt clusters (1.2 nm) on multi-walled carbon nanotubes (MWNTs) by the aid of NaOH in a reduction process. The electrocatalyst loses 50% of the initial electrochemical surface area (ECSA) after 200 000 potential cycles from 1.0 to 1.5 V vs. RHE, which is 20 times higher compared to commercial CB/Pt. The mass power density of the Pt cluster electrocatalyst measured under 120 °C without any humidification reaches 1320 mW mg_Pt⁻¹, which is 6.7 times higher compared to that of commercial CB/Pt. To the best of our knowledge, the mass power density of our electrocatalyst is one of the highest values measured in high-temperature PEFCs.