Photocatalytic　syngas　(CO　and　H2)　production　with　CO2　as　gas　source　not　only　ameliorates　greenhouse　effect,　but　also　produces　valuable　chemical　feedstocks.　However,　traditional　photocatalytic　systems　require　noble　metal　or　suffers　from　low　yield.　Here,　we　demonstrate　that　S　vacancies　ZnIn2S4　(VS-ZnIn2S4)　nanosheets　are　an　ideal　photocatalyst　to　drive　CO2　reduction　into　syngas.　It　is　found　that　building　S　vacancies　can　endow　ZnIn2S4　with　stronger　photoabsorption,　efficient　electron–hole　separation,　and　larger　CO2　adsorption,　finally　promoting　both　hydrogen　evolution　reaction　(HER)　and　CO2　reduction　reaction　(CO2RR).　The　syngas　yield　of　CO　and　H2　is　therefore　significantly　increased.　In　contrast　to　pristine　ZnIn2S4,　the　syngas　yield　over　VS-ZnIn2S4　can　be　improved　by　roughly　≈4.73　times　and　the　CO/H2　ratio　is　modified　from　1:4.18　to　1:1.　Total　amount　of　syngas　after　12　h　photocatalysis　is　as　high　as　63.20　mmol　g−1　without　use　of　any　noble　metals,　which　is　even　higher　than　those　of　traditional　noble　metal-based　catalysts　in　the　reported　literatures.　This　work　demonstrates　the　critical　role　of　S　vacancies　in　mediating　catalytic　activity　and　selectivity,　and　highlights　the　attractive　ability　of　defective　ZnIn2S4　for　light-driven　syngas　production.　©　2020　Wiley-VCH　GmbH