Abstract The CsPbBr 3 quantum dots (QDs) modified vertically layered MoS 2 /Si (V‐MoS 2 /Si) heterojunction is successfully prepared. It is found that the resulting photodetector realizes the UV–vis–NIR broad‐spectrum detection with good sensitivity and fast photoresponse speed. Typically, the responsivity and response/recovery time towards 808 nm reach up to 0.975 A W −1 and 6.8/6.7 ms, respectively. Furthermore, it is demonstrated that with the modification of CsPbBr 3 QDs, the responsivities of the pure V‐MoS 2 /Si‐based photodetector for 532, 671, and 808 nm detection are boosted by 5.43, 2, and 5.45 times, respectively. The enhanced sensing performance is attributed to the vis–NIR light harvesting capability and excellent electrical transporting property of the CsPbBr 3 QDs. Most importantly, the flexibility can be applied to the wearable devices for various working environments. The present work pushes the development of the flexible devices for broadband spectrum detection faced to practical application.