<p>The development of efficient electrocatalysts for CO₂-to-C₂₊ conversion necessitates precise engineering of active sites and intermediate regulation. Herein, we present atomically dispersed Cu–O–Si bifunctional sites embedded within ordered mesoporous silica, which synergistically promote the efficient electroreduction of CO₂ to multicarbon products. In contrast to conventional single-atom catalysts, the Cu–O–Si configuration enables cooperative active sites where SiO₂’s intrinsic activity facilitates the generation of *CO intermediates, while the atomic Cu centers promote C–C coupling. This dual functionality allows the catalyst to achieve 73.9% C₂₊ Faradaic efficiency at 400 mA cm⁻², surpassing that of benchmark Cu-based single-atom catalysts. Experimental investigations further confirm that pristine SiO₂ exhibits a CH₄ Faradaic efficiency of 36.19%–39.51%, highlighting its previously unrecognized catalytic contribution. Operando spectroscopic analysis reveals that the ordered mesoporous structure enhances *CO surface coverage and suppresses un-desired proton transfer pathways. Density functional theory (DFT) calculations demonstrate that *CO species preferentially migrate from Si to Cu active sites, where the C–C coupling barrier is as low as −2.283 eV. This work demonstrates that carrier-induced bifunctionality is viable for practical CO₂ electrolyzers, establishing oxide supports as active partners in scalable carbon valorization.</p>