Abstract Semiconductor heterostructure nanowires (HNWs) are excellent candidates for application in compact optoelectronics devices with high performance due to the heterojunction interface effect. However, the controllable fabrication of high‐quality nano‐heterostructures is elusive. In this paper, the controllable growth and optoelectronics device application of high‐quality ZnS 0.49 Se 0.51 /ZnSe axial HNWs are reported. The as‐synthesized HNWs are straight with uniform diameter distribution of 50–100 nm. Microstructural characterization reveals single crystal and abrupt heterojunction interface in these HNWs. The micro‐photoluminescence of single component region and heterojunction zone show one and integrated two near bandgap emission of ZnS 0.49 Se 0.51 and ZnSe, respectively, further demonstrating the abrupt heterojunction interfaces nature in the as‐grown nanowires. Moreover, photodetectors based on single HNW are fabricated and the responsivity, external quantum efficiency, response speed, and detection wavelength range are superior to that of single component nanowire photodetectors at room temperature. These results show that the ZnS 0.49 Se 0.51 /ZnSe HNWs and corresponding high‐performance photodetectors are prospective candidates for photonics and optoelectronics applications.