Diabetic kidney disease (DKD) is a main cause of end-stage renal disorder, yet its pathogenesis is still incompletely understood. Ferroptosis has been implicated in DKD progression; however, its regulatory mechanisms remain unclear. Phosphoglycerate dehydrogenase (PHGDH), a key enzyme in serine biosynthesis, has been minimally studied in DKD development. To elucidate the roles of PHGDH in ferroptosis and its underlying mechanism in podocytes and DKD, we conducted this study. Our findings demonstrate that PHGDH deficiency exacerbates podocyte injury, characterized by cytoskeletal disorganization, and promotes ferroptosis in both podocytes and DKD renal tissues. Conversely, PHGDH overexpression alleviates podocyte injury, reduces ferroptosis, and improves renal function in DKD mice. Mechanistically, we identified that PHGDH mediates ferroptosis by regulating SLC7A11 expression, a key ferroptosis-related protein. Specifically, PHGDH stabilizes Y-box binding protein 1 (YB1) by inhibiting its K48-linked ubiquitination and degradation, thereby enhancing SLC7A11 mRNA stability and expression. In conclusion, our study reveals a novel PHGDH-YB1-SLC7A11 regulatory axis that is responsible for suppressing ferroptosis and protecting against podocyte and renal injury in DKD. Our findings shed new light into the molecular mechanism underlying ferroptosis in DKD and highlight PHGDH as a therapeutic target for mitigating ferroptosis-mediated renal damage.