In this study, we evaluated the feasibility of using CO₂+N₂O mixed gas hydrates for the development of advanced greenhouse gas (GHG) sequestration technology. Structural characteristics of gas hydrates at different mole fractions of the gas mixture (CO₂:N₂O = 0.7:0.3 and 0.5:0.5) was analyzed using Raman spectroscopy and high-resolution X-ray powder diffraction. The mixed gas hydrates can contain both CO₂ and N₂O molecules simultaneously, in small and large cages of structure I hydrate without structural deformation. Their volume can be expanded by increase of the N₂O portion. The phase equilibrium condition of the mixed gas hydrates was more stable than that of pure CO₂ hydrates, and estimated dissociation enthalpies of the mixed gas hydrates were higher than those of the CO₂ hydrates. We confirmed that the mixed gas hydrates can reduce massive amounts of GHG emissions due to their potentially higher storage capacity. These research results provide basic knowledge useful for the simultaneous mitigation of the effects from major GHGs and application of the CO₂+N₂O mixed hydrates to advanced offshore GHG sequestration in marine sediment environments.