Objective To investigate the predictive value of the neutrophil-to-lymphocyte ratio (NLR) for complicated acute kidney injury (AKI) in patients with multiple injuries. Methods The clinical data of 87 patients with multiple injuries were retrospectively analyzed, and the patients were divided into an AKI group or a non-AKI group according to whether they had complicated AKI during hospitalization. The two groups of patients were compared in age, gender, comorbidities (diabetes mellitus, hypertension), and injury severity score (ISS), as well as the mean arterial pressure, blood routine test results, and renal function at admission. The binary logistic regression model was used to analyze influencing factors for AKI in patients with multiple injuries, and the receiver operating characteristic (ROC) curve was plotted to analyze the predictive value of NLR for AKI in patients with multiple injuries. Results There was no statistically significant difference in age, gender, comorbidities (diabetes mellitus, hypertension), white blood cell count at admission, hemoglobin level at admission, C-reactive protein level at admission, or serum creatinine level at admission between the AKI group and the non-AKI group (all P>0.05). The ISS and the NLR at admission of the AKI group were higher than those of the non-AKI group, and the mean arterial pressure at admission of the AKI group was lower than that of the non-AKI group (all P<0.05). The results of the binary logistic regression analysis showed that a high NLR at admission was an independent risk factor for AKI in patients with multiple injuries (P<0.05). The results of the ROC curve analysis showed that the sensitivity and specificity of NLR in predicting AKI in patients with multiple injuries were 73.3% and 83.3%, respectively, while the area under the ROC curve was 0.781 (P<0.05). Conclusion The elevated NLR is an independent risk factor for complicated AKI in patients with multiple injuries, and the NLR can be used as an early predictor of complicated AKI in patients with multiple injuries.