We present the fabrication of highly durable catalyst with the graphitized carbon (GC) via diazonium chemistry for polymer electrolyte membrane fuel cell (PEMFC). The functionalization of the GC with the trifluoromethylphenyl groups by diazonium reaction was shown to enhance the distribution of Pt nanoparticles deposited on the functionalized GC surfaces and reduce their agglomeration, resulting in higher stability of Pt catalysts with enhanced activity as compared to the Pt/unmodified GC and a commercial Pt/C catalyst. The durability of the Pt/functionalized GC depends on the uniform distribution of Pt nanoparticles and the surface-grafted layers on the GC surfaces. The enhanced durability of the Pt/functionalized GC results from the combined effect of the in situ grafted layers acting as effective barriers for the migration of Pt nanoparticles and subsequent their agglomeration on the GC surfaces and the slow-down of the kinetics of the carbon oxidation reaction induced by high degree of graphitization. This study suggests that a facile functionalization through simple diazonium reaction in an effective way to fabricate highly durable Pt catalysts with enhanced activity for PEMFC, providing a design guide of functionalized carbon supports with a great potential as a PEMFC catalyst.