Antimony selenide (Sb₂Se₃) has many potential applications in photoelectric devices, thermoelectric cooling devices and electrochemical devices etc. It also has many special properties due to its layered structure. A simple hydrothermal method was used to synthesize Sb₂Se₃ nanowires of high crystalline quality. (Sb₄Se₆)_n layers are parallel to the growth direction of the Sb₂Se₃ nanowire. A single Sb₂Se₃ nanowire demonstrated a remarkable response to 635 nm light at 10 V with the responsivity and external quantum efficiency of 360 A W⁻¹ and 7.0 × 10⁴%, respectively. The rise/fall time was 0.4/1.3 s. Flexible photodetectors were fabricated by dispersing a large number of Sb₂Se₃ nanowires onto the Au interdigitated electrodes on PET substrates, which showed a fast response speed with the rise/fall time as low as 13/20 ms and excellent flexibility. The high-performance of the photodetectors may be partially attributed to the layered structure. Generally, high-yield Sb₂Se₃ nanowires synthesized by the hydrothermal method are promising candidates for high-performance flexible photodetectors.