Facet-engineered MIL-88B catalysts with tunable {011}/{010} were designed via a facile pathway. CO2 photoreduction tests revealed a pronounced facet-dependent catalytic performance. Highly exposed facets {010} and {011} separately promoted the formation of C2H4 and CO. Detected pivotal intermediates indicate that facet {010} can facilitate the conversion of CO2 to C2+ C2H4.