We propose a new mechanism for destabilizing Mg-H bonding by means of a combination of the size effect and MgH2-carbon scaffold interfacial bonding, and experimentally realize low temperature hydrogen release starting from 50 °C using an MgH2@CMK-3 nanoconfinement system (37.5 wt% MgH2 loading amount). Based on computational calculations, it is found that the charge transfer from MgH2 to the carbon scaffold plays a critical role in the significant reduction of thermodynamics of MgH2 dehydrogenation. Our results suggest how to explore an alternative route for the enhancement of nano-interfacial confinement to destabilize the Mg-H hydrogen storage system.