This study reveals that low blue light (LBL) induces premature leaf senescence in soybean through a regulatory pathway involving GmCRY1s, DELLA proteins, and GmWRKY100. Under shaded conditions, reduced blue light levels trigger leaf senescence by disrupting the interaction between GmCRY1s and DELLA proteins, leading to the degradation of DELLA proteins and the upregulation of GmWRKY100, which promotes senescence. GmCRY1s stabilize DELLA proteins, which in turn suppress GmWRKY100 transcription, delaying senescence. When LBL occurs, the interaction between GmCRY1s and DELLA proteins is disrupted, leading to DELLA protein degradation and increased GmWRKY100 expression, thus accelerating senescence. The study identifies a GmCRY1s-GmDELLAs-GmWRKY100 regulatory cascade that mediates LBL-induced leaf senescence in soybean. Additionally, GmWRKY100 knockout soybeans exhibit delayed leaf senescence and improved yield under natural field conditions, suggesting potential applications in enhancing soybean production by manipulating the leaf senescence trait. The findings provide insights into how light signals regulate leaf senescence and highlight the importance of understanding the molecular mechanisms underlying this process for improving crop yield and quality.This study reveals that low blue light (LBL) induces premature leaf senescence in soybean through a regulatory pathway involving GmCRY1s, DELLA proteins, and GmWRKY100. Under shaded conditions, reduced blue light levels trigger leaf senescence by disrupting the interaction between GmCRY1s and DELLA proteins, leading to the degradation of DELLA proteins and the upregulation of GmWRKY100, which promotes senescence. GmCRY1s stabilize DELLA proteins, which in turn suppress GmWRKY100 transcription, delaying senescence. When LBL occurs, the interaction between GmCRY1s and DELLA proteins is disrupted, leading to DELLA protein degradation and increased GmWRKY100 expression, thus accelerating senescence. The study identifies a GmCRY1s-GmDELLAs-GmWRKY100 regulatory cascade that mediates LBL-induced leaf senescence in soybean. Additionally, GmWRKY100 knockout soybeans exhibit delayed leaf senescence and improved yield under natural field conditions, suggesting potential applications in enhancing soybean production by manipulating the leaf senescence trait. The findings provide insights into how light signals regulate leaf senescence and highlight the importance of understanding the molecular mechanisms underlying this process for improving crop yield and quality.