The effects of blue light-emitting diodes (LEDs) on postharvest chilling injury were examined in a representative chilling-sensitive vegetable. Cucumbers were divided into two groups: the first group was placed in constant darkness; the second group was irradiated with 460 nm blue LED light at 45 W•m-2 for 12 h every day. All cucumbers were stored at 4 ℃ for ten days. Chilling injury indicators, quality parameters, and reactive oxygen species (ROS) metabolism were analyzed every two days. The results demonstrated that compared to the control group, blue LED treatment significantly reduced the chilling injury index by 30% and decreased the weight loss rate by 11.69%, while also effectively maintaining higher firmness, L*, chlorophyll, and soluble solids in cucumber. Furthermore, blue LED treatment increased total phenolic and flavonoid content, as well as antioxidant enzyme activities, thus, collectively enhancing free radical scavenging capacity and reducing superoxide anion (O2-) content. Therefore, blue LED irradiation mitigates chilling injury and preserves postharvest quality in cucumber by activating antioxidant systems, thereby maintaining oxidative homeostasis. The results of this study provide the LED preservation conditions required to extend the low-temperature storage of cucumbers and reduce postharvest losses.