The development of a highly efficient and secure system for hydrogen storage and delivery is currently imperative, yet has great challenges. Herein, a series of highly dispersed and small cobalt nanoparticles supported by MOF-derived hierarchically porous carbon were synthesized by employing a selective atom evaporated-isolation strategy with bimetal Co/Zn-MOF-74 used as sacrificial template. The formation of ultrasmall Co nanoparticles in the hierarchically porous carbon was largely due to the assistance of doped Zn atoms in Co/Zn-MOF-74 precursors, which restricted their agglomeration during pyrolysis. Detailed catalytic results indicated that both the mole ratio of Co/Zn and the pyrolysis temperature were crucial to modulate their dehydrogenation performance for ammonia-borane, of which the as-synthesized 30% Co/HPC catalyst pyrolyzed under 900 degrees C exhibited the highest catalytic activity. Furthermore, these Co/HPC catalysts also showed good structure stability and magnetically reusability, which, together with the superior activity, enabled them to hold great promise for practical applications.