The atmospheric level of nitrous oxide (N2O), a representative greenhouse gas, is increasing, and the decomposition of N2O generally requires an energy-intensive reaction. This study introduces a nano-sized cage of ionic clathrate hydrate as a nanoreactor to decompose N2O. Ionic species, (Me)4N+ and OH−, are injected to boost electron transfer in the activated water-framework of ionic clathrate hydrate. Molecular N2O is captured in empty cages and decomposed to non-greenhouse gases of nitrogen and oxygen by the transferred electrons from the methyl radical decay. This suggests that the clathrate hydrate can be used for both the sequestration and treatment of greenhouse gases.