Synthesizing the catalysts with high activity and stability has always been the research hotspot in the field of heterogeneous catalysis, and the confinement provides a promising route to achieve the goal. Herein we report the porous TiO2 nanotube confined Pt catalysts synthesized by the template-assisted atomic layer deposition (ALD) strategy for hydrolytic dehydrogenation of NH3BH3, in which the ultrafine Pt nanoparticles are decorated on the inner surfaces of the nanotubes with increased Pt-TiO2 interfacial sites compared with the supported Pt/TiO2 counterparts. Combined with the porous structures of the nanotubes with suitable thickness and large open ends, these factors synergistically contribute to the excellent catalytic performances of the confined [email protected]2 catalysts. The present strategy can be extended to prepare the corresponding [email protected]2 bicomponent catalysts exhibiting the further boosted activity with a TOF value of 1055.2 molH2 molPt−1 min−1. This work offers a reliable and general approach for synthesizing the confined catalysts with high efficiency.