Herein, an oxidation‐controlled SnS2 gas sensor is reported. Different oxidation levels of SnS2 are constructed by adjusting the dosage ratio of reagents. The sensing response of oxidized SnS2 to NH3 is studied, and the working mechanism is explored. Results demonstrate that the different oxidation levels of SnS2 exhibit significantly improved gas‐sensing properties. In particular, oxidation‐controlled SnS2 (SnS2‐2 sample) shows a high response to NH3 (92 000%) with a fast response recovery time (17/2 s). The novelty of this work lies in the simple synthesis of SnS2 with oxidation regulation and its application as a high‐sensitivity NH3 gas sensor at room temperature. [ABSTRACT FROM AUTHOR]