Copyright © 2018 American Chemical Society. In artificial photosynthesis, the establishment of design guidelines for nanostructures to maximize the photocatalytic performance remains a great challenge. In contrast with the intense research into band-offset tuning for photocatalysts, the relationship between nanostructures and photoinduced carrier dynamics has still been insufficiently explored. We synthesized durian-shaped CdS@ZnSe core@mesporous-shell nanoparticles (d-CdS/ZnSe NPs) and investigated the carrier dynamics in photocatalytic hydrogen evolution. The cocatalyst-free d-CdS/ZnSe NPs exhibited high photocatalytic activity for H2 evolution (14.8% apparent quantum yield at 420 nm) and excellent stability (maintaining 80% activity after 72 h) under visible-light irradiation (>422 nm). The transient absorption measurement and flash photolysis time-resolved microwave conductivity unveiled that the ultra-long-lived charge separation (>6.2 ms) and swift hole transfer to the surfaces of ZnSe shell (11 ns) contribute the high catalytic activity and stability. The present work provides a novel insight into designing nanoparticulate photocatalysts with optimized performance.