Exploring advanced non-noble metal-based catalysts for H2 release from chemical hydrogen storage materials is of paramount importance to boost hydrogen economy. Rationally tailoring over architecture and electronic state promises high-efficiency catalysis. Herein we present, for the first time, delicate engineer of cobalt phosphide with a unique porous, multishelled, and hollow architecture (multishelled Co-P) for dramatically promoting ammonia borane (AB) dehydrogenation. Featuring hollow porous structure and complex nanoconfined interior space, multishelled Co-P possesses abundant accessible active sites and facile mass transfer. Importantly, theoretical calculations decipher that P incorporation in Co-P can modulate electronic structure of Co sites to give promoted H2O adsorption and favorable H2O dissociation kinetics (rate-determining step), thereby facilitating AB dehydrogenation. This study provides a fundamental understanding of correlation between electronic state of Co-P and AB dehydrogenation behavior, and highlights that decent architectural engineering coupled with electronic modulation is an effective protocol to construct advanced catalytic systems.