The stability of glucose oxidase (GOx) immobilized on a silicon electrode can be enhanced using spatial confinement as described in this paper. We show that when GOx is assembled in semiopen spatially confined structures created on the unmodified surface of a silicon electrode, the enzyme's activity is preserved under destabilizing conditions. GOx-immobilized silicon electrodes were treated with guanidinium chloride and high temperature. Cyclic voltammetry measurement of the treated electrodes showed the proper redox characteristics of GOx and indicated the GOx-catalyzed electrooxidation of glucose. When GOx was immobilized on flat silicon electrodes, voltammetric measurement showed null result presumably caused by denaturation of the enzyme. The effect of spatial confinement on enzyme stability is also revealed by analyzing the characteristic rate constants and the kinetic parameter for the complete catalytic process of glucose.