Proper thermal management is the key to the efficient and safe operation of proton exchange membrane fuel cells. In this study, a novel vapor chamber was designed and experimentally tested to verify its potential application for proton exchange membrane fuel cell cooling. The thermal management design scheme of proton exchange membrane fuel cells based on vapor chambers was introduced, and the influence of structural parameters on the theoretical maximum heat transfer of the vapor chamber was discussed. Based on theoretical analysis, a vapor chamber matching the structural characteristics of proton exchange membrane fuel cells was designed and manufactured, and the influence of heat load, tilt angle, and cooling water flow rate on the heat transfer performance of the vapor chamber was investigated experimentally. The results showed that the designed vapor chamber had excellent thermal dispersion performance and temperature equalization ability. When the heat load was less than 35 W, the maximum temperature of the vapor chamber was always less than 33 °C, and the thermal resistance was less than 0.2 °C/W. The tilt angle affected the capillary limit of the vapor chamber, and then significantly affected the thermal performance of the vapor chamber. In addition, the results also indicated that increasing the cooling water flow rate led to an increase in the temperature difference and thermal resistance of the vapor chamber, but this effect was relatively limited. The results of this study will provide a new idea and reference for the efficient thermal management of proton exchange membrane fuel cells.