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Low durability and fuel cell performance block the widespread application of polymer electrolyte fuel cells (PEFCs). Here, we deposit platinum nanoparticles on carbon nanotubes (CNTs) before coating by end-capped hyperbranched sulfonated macromolecules (E-HBM), which could provide sufficient proton conductivity in catalyst layer thanks to the presence of −SO3H groups. The fabricated electrocatalyst loses 43 % of initial electrochemical surface area (ECSA) after 200 000 potential cycles from 1.0 V to 1.5 V vs. RHE, which is 3 and 20 times higher than that of noncoated and commercial electrocatalysts, respectively. The mass and specific activities of newly fabricated electrocatalyst measured before and after durability test are 1.4 times higher than that of commercial carbon black/Pt. Nafion ionomer-free membrane electrode assembly is fabricated from the newly designed electrocatalyst, and its fuel-cell performance reaches 668 mW cm−2 with Pt loading of 0.1 mg cm−2, which is twice higher than that of commercial CB/Pt thanks to the homogeneous conductive macromolecules (E-HBM) layers on CNTs acting as ionomer and facilitating the proton delivery in the catalyst layer. [ABSTRACT FROM AUTHOR]