Cocatalysts loading is one of the most effective strategies for boosting CO2 photoreduction. Thus, constructing robust active sites with a specific chemical environment on the cocatalyst to selectively convert CO2 to chemical fuels is highly desirable, but remains challenging. Herein, α-Fe2O3 platelets modulated with confined Co centers and oxygen defects are designed as efficient cocatalysts for photocatalytic CO2 reduction with superior activity and CO selectivity. The highly dispersed Co centers can proceed the catalytic processes efficiently as the reaction sites, while the oxygen vacancies enable to enhance the CO2 adsorption/activation. After integrating together, the oxygen defects provide vigorous assistances to promote the catalytic activity of confined Co sites, leading to facilitated charge transfer and reduced energy barriers for CO2 photoreduction. As a result, the optimized catalyst achieves a CO generation rate of 37.8 μmol h−1 with an impressive selectivity of 80.2%, as well as remarkable durability for photocatalytic CO2 reduction. This work demonstrates new insights of developing robust catalysts by controlling confined active sites together with defects engineering for efficient photocatalytic CO2 conversion.