Summary: Flexible short-wavelength infrared (SWIR) detectors are significant for wearable health monitoring, artificial vision systems, etc. However, it is difficult to realize flexibility in mainstream SWIR photodetectors, like InGaAs and HgCdTe, because of high fabrication temperature and epitaxial growth on single-crystal substrates. Herein, we report a highly flexible thin-film transistor (TFT) monolithic-integrated SWIR photodetector based on one-dimensional (Bi,Sb)2Se3. A high external quantum efficiency of 29% at 1,300 nm and fast response time are achieved. The device exhibits excellent flexibility due to the high mechanical tolerance of the one-dimensional structure, retaining 97% of the original value after bending at a 0.05 mm radius. It also presents high electric and thermal stability, maintaining 97.6% of the original value after annealing for 408 h at 90°C. Finally, applications for wearable heart rate monitors and curved-surface imaging are demonstrated. This work highlights the potential of (Bi,Sb)2Se3 SWIR photodetector for flexible electronics.