The FAPbBr 3 /g-C 3 N 4 heterostructures show excellent photocatalytic activity for NO reduction under visible light irradiation. • An FAPbBr 3 /g-C 3 N 4 heterojunction is a new type of photocatalytic composite. • FAPbBr 3 /g-C 3 N 4 composites show excellent NO removal efficiency under irradiation. • The best removal rate is 58%, which is much higher than that of FAPbBr 3 and g-C 3 N 4 . • The photocatalytic mechanism of Type-II heterojunction for NO removal is discussed. Previously, many methods have been used to reduce NOx pollution. Semiconductor photocatalytic oxidation technology has been widely used among those methods because of its environmental friendliness, high efficiency, and simple implementation. Hybrid halide perovskites with exceptional optical properties prove to be promising photocatalysis material; however, their high surface energy, unpaired bonds, and instability are obstacles to large-scale application. In this work, FAPbBr 3 /g-C 3 N 4 heterostructures were successfully synthesized by growing FAPbBr 3 nanocrystals on 2D g-C 3 N 4 nanosheets. Compared with the pristine elements, FAPbBr 3 /g-C 3 N 4 composites show significant NO removal efficiencies under 600 ppb concentration at room temperature. The high performance could be attributed to the formation of a type-II heterojunction and accelerated the separation and transfer of electrons and holes. Furthermore, cycling experiments and XRD results verify that the FAPbBr 3 /g-C 3 N 4 heterojunction owns good stability. Thus, this work not only shows the great potential prospect of halide perovskite for the photocatalysis field, but also demonstrate its promise in solving energy issues and environment science.