microRNA-210 (miR-210), the master hypoxamir, is overexpressed and generally exhibits oncogenic properties in most human solid tumours, including colorectal cancer (CRC). However, the status of circulating miR-210 in CRC is still unknown. This study aims to assess the clinical significance of circulating miR-210 in CRC. Using (reverse transcription quantitative PCR) RT-qPCR analysis, we compared the expression levels of circulating miR-210 in serum of 268 CRC patients and 102 healthy controls, and found that serum miR-210 was significantly higher in CRC than in healthy controls (P < 0.001). The area under the receiver operating characteristic curve (AUC) of circulating miR-210 to detect CRC was 0.821, with a sensitivity of 74.6% and a specificity of 73.5%. The AUC of circulating miR-210 showed significantly higher detection capability than that of carcinoembryogenic antigen (P < 0.05). Kaplan-Meier analysis demonstrated that increased serum miR-210 level correlated with reduced overall survival (OS) and disease-free survival (DFS) (P = 0.008 and P = 0.008 respectively). Cox analysis indicated circulating miR-210 was an independent prognostic factor for OS and DFS. Taken together, our data suggested that circulating miR-210 could be a potential non-invasive marker for diagnosis and prognosis of CRC.