Objective To assess the prognostic significance of serum cystatin C （CysC） in combination with bedside renal ultrasound for patients diagnosed with sepsis-induced acute kidney injury （AKI）. Methods The study cohort comprised 134 patients with sepsis-induced AKI who were admitted to our hospital between October 2019 and October 2023. Based on the 30 day prognosis， the patients were categorized into a survival group （n = 93） and a death group （n = 41）. Collected clinical data included gender， age， heart rate， underlying diseases， treatment modalities， duration of hospital stay， basic biochemical indicators， and Acute Physiology and Chronic Health Evaluation Ⅱ（APACHEⅡ） scores. Renal function markers such as serum creatinine （SCr）， blood urea nitrogen （BUN）， and cystatin C levels were measured； renal blood flow resistance index （RI） was assessed using bedside routine ultrasound. Cox regression analysis was employed to evaluate factors influencing poor prognosis in patients with sepsis-induced AKI while analyzing the prognostic assessment value of combining cystatin C with bedside renal ultrasound through ROC curves. Results The death group exhibited significantly higher APACHEⅡ scores， SCr， BUN， CysC levels， and RI （all P < 0.05） compared to the survival group. Cox regression analysis revealed that both CysC levels and RI were significant prognostic indicators （P < 0.05）. ROC curve analysis demonstrated that the combined assessment of CysC levels and RI yielded a high diagnostic accuracy of 97.5% in predicting outcomes for patients with sepsis-induced AKI. Conclusion CysC levels and bedside renal ultrasound can serve as prognostic indicators for patients with sepsis-induced acute kidney injury （AKI）， thereby guiding clinical treatment.