Diabetic nephropathy (DN) is a leading cause of chronic kidney disease (CKD), affecting nearly one-third of CKD patients. As CKD advances, it may progress to end-stage renal disease, necessitating dialysis or transplantation. Hyperglycemia-driven metabolic and hemodynamic disturbances contribute to oxidative stress, inflammation, and fibrosis. Since current treatments remain insufficient, novel therapeutic strategies are urgently needed to halt DN progression. Stachybotrys microspora triprenyl phenols (SMTPs), the focus of our research, exhibit anti-inflammatory properties and have shown therapeutic potential in various disease models. We aimed to evaluate the efficacy of SMTP-27 in a DN mouse model. DN was induced by removing the right kidney of db/db mice. The efficacy of SMTP-27 was determined by evaluating the renal function using urine and serum samples and morphological assessment of the kidney tissues. For deciphering the mechanism of action of SMTP-27, markers associated with inflammatory signaling pathways in the kidney were detected. SMTP-27 (0.03, 0.3, 3, 30 mg/kg) dose-dependently improved the renal function. In addition, it improved the mesangial matrix overproduction, podocyte injury, and renal tubule injury and exhibited anti-inflammatory activity in the kidneys of mice with DN. These results indicate the potential of SMTP-27 as a novel therapeutic strategy for DN.