Recently, hydrolysis of ammonia borane (AB) is a promising way of producing and employing hydrogen in mild conditions. Nonetheless, the failure to develop inexpensive and high-performance catalyst impedes the further scale hydrogen energy application of AB. Given the fact that ex-situ formed nanocatalysts could be prone to abscission and agglomeration for insufficient dispersion and support, 1D composite microrods with 0D/1D/2D spatial structure constructed by mutual-supported 2D single-crystal Co₂Mo₃O₈ nanosheets and 0D Co nanoparticles (denoted as Co@Co₂Mo₃O₈) have been in-situ synthesized and introduced into the hydrolysis of AB for the first time. Excitingly, the novel Co@Co₂Mo₃O₈ exhibits one of the best catalytic performances in the hydrolysis of AB for non-noble metal/metal oxide heterojunction catalysts with TOF value reaching 17.28 ${\text{mol}}_{{\text{H}}_{\text{2}}}{\text{mol}}_{\text{Cat}}^{\text{-1}}{\text{min}}^{\text{-1}}$ at 25 °C, which is 3.95 and 24.0 times that of the single Co₂Mo₃O₈ and Co. Meanwhile, two kinds of catalytic components with high intrinsic activity (Co₂Mo₃O₈ and Co) and supporting each other in the 0D/1D/2D spatial structure (nanoparticles, microrods, and nanosheets) along with plentiful O vacancies induce the outstanding catalytic activity of Co@Co₂Mo₃O₈. The large-scale controllable preparation method for in-situ fabrication of non-noble metal 0D/1D/2D composite catalysts with high performances would be an accelerator for great potential application for hydrolysis of AB.