Background: Acute kidney injury (AKI) is a relatively common complication after surgery for type A acute aortic dissection (ATAAD) and is associated with a poor prognosis. Preclinical models suggest that toll-like receptor 4 (TLR4) may participate in the pathogenesis of AKI. However, the correlation of serum TLR4 and post-operative AKI has not been studied in ATAAD patients. This study aimed to explore the possibility of using serum TLR4 levels to predict AKI and 30-day mortality in patients undergoing ATAAD surgery. Methods: A prospective, single-center cohort study was conducted and enrolled a total of 64 patients undergoing ATAAD surgery. The level of serum TLR4 was measured and compared before and within 24 hours after the completion of surgery. Results: Thirty-five (54.7%) patients developed AKI, including 7 (10.9%) diagnosed with severe AKI (Kidney Disease Improving Global Outcomes (KDIGO) stage 3). TLR4 levels at 0-hour,1-hour, 3-hour, and 6-hour after intensive care unit (ICU) admission were significantly different between patients with or without AKI. Further analysis showed that the difference was most significant at 0-hour after ICU admission which corresponded to an area under the curve (AUC) of 0.886 (95% confidence interval (CI), 0.800 to 0.973). For severe AKI, the AUC of TLR4 was the highest with 0.923 (0.852 to 0.995) at 1-hour after ICU admission. TLR4 levels before surgery and at 0-hour, 1-hour, as well as 3-hour after ICU admission were significantly different between survivors and non-survivors. Furthermore, we found that the serum level of TLR4 upon ICU admission could be used to predict the 30-day mortality with AUC of 0.805 (0.648 to 0.962). Conclusions: Serum TLR4 levels can be used as a biomarker to predict the occurrence of AKI and 30-day mortality in patients undergoing ATAAD surgery. Clinical Trial Registration Number: ChiCTR2200057197.