Here, we demonstrate the SnS/g-C₃N₄ crystallized and nanostructured photocatalysts for efficient and selective CO₂ conversion to CH₄ by engineered thermal evaporation and the decoration of g-C₃N₄ through a simple dipping method, overcoming the limitation of bulk SnS-based photocatalysts. The SnS/g-C₃N₄ nanostructured photocatalysts exhibit a superior methane production rate of 387.5 μmol∙m⁻²∙h⁻¹ (= c.a. 122.33 μmol∙g⁻¹∙h⁻¹) with an apparent quantum yield of c.a. 9.7% at 520 nm with engineered lengths. Moreover, 100% selective production toward CH₄ is also measured from the SnS/g-C₃N₄ photocatalysts, with > 10 h stable operation. These performances are, to the best of our knowledge, the highest production rate among reported photocatalytic films and metal sulfide/g-C₃N₄ composite-based photocatalysts. These highly improved performances are attributed to synergistic effects by the …