The optimal measuring timing of Cystatin C (CysC) for early detection of contrast-induced acute kidney injury (CIAKI) remains un-studied. We conducted this systematic review and meta-analysis study to elucidate further on this issue. We searched PubMed, MEDLINE, and Embase from inception until March 2018 for studies evaluating the diagnostic accuracy of CysC for predicting CIAKI in patients exposed to contrast agents during diagnostic examinations or cardiac/peripheral catheterizations. A total of 10 relevant studies, comprising 2554 patients, were included. The included studies were divided into two groups: <24-hour and 24-hour groups, based on CysC measuring timing (i.e., hours after contrast agent exposure). Compared with creatinine, the pooled diagnostic odds ratio of CysC for detecting CIAKI of the <24-hour and 24-hour groups was 7.59 and 53.81, respectively. The pooled sensitivity of the <24-hour and 24-hour groups was 0.81 and 0.88, respectively. The pooled specificity of the <24-hour and 24-hour groups was 0.64 and 0.88, respectively. The area under the hierarchical summary receiver operating characteristic curve of the <24-hour and 24-hour groups was 0.75 and 0.93, respectively. Collectively, these data indicate that 24 hours after contrast agent exposure is the optimal measuring timing of CysC for early detection of CIAKI.