Ternary　transition　metal　tungstates　with　low　cost,　high　stability,　and　narrow　band　gap　have　exhibited　great　opportunities　for　photocatalysis,　but　their　application　in　CO2　photoreduction　is　much　less　reported.　Herein,　we　present　the　synthesis　of　mesoporous　ternary　cobalt　tungstate　(CoWO4)　nanostructures　as　an　advanced　cocatalyst　for　photocatalytic　CO2　reduction.　A　series　of　CoWO4　samples　are　prepared　via　a　facile　one-step　hydrothermal　method　at　different　temperatures　and　fully　checked　by　diverse　physicochemical　characterizations.　The　crystallinity　and　microstructure　of　CoWO4　can　be　facilely　modulated　by　changing　the　synthesis　temperature.　In　a　classic　tandem　visible-light-sensitized　system,　the　optimal　CoWO4　cocatalyst　affords　excellent　activity　and　stability　for　deoxygenative　CO2　reduction,　with　a　CO-yielding　rate　of　52.1　mmol　h(-1)　(i.e.　17.4　mmol　h(-1)　g(-1)),　which　is　22　times　higher　than　the　system　without　the　cocatalyst.　The　collective　photoelectrochemical　measurements　disclose　that　the　cocatalyst　can　promote　separation　and　migration　of　the　charge　carriers　and　provide　abundant　active　sites　to　activate　and　reduce　CO2　molecules,　thus　boosting　CO2　reduction.　This　work　may　promote　more　research　attention　on　exploring　ternary　transition　metal　tungstates　as　high-efficiency　cofactors　for　CO2　photoreduction.　(C)&　nbsp;2022　Elsevier　Ltd.　All　rights　reserved.