We investigated the association between plasma microRNA (miR)-204 and coronary artery calcification (CAC) in patients with type 2 diabetes mellitus (T2DM). We consecutively enrolled 179 individuals with T2DM who underwent coronary computed tomography at Anzhen Hospital from January 2015 to September 2016. The CAC score (CACS) was expressed in Agatston units and >10 Hounsfield units were defined as CAC-positive status. Significant CAC was observed in 98 (54.7%) patients. Plasma miR-204 levels (relative expression) were significantly lower in patients with significant CAC than controls (1.001 ± 0.100 vs 0.634 ± 0.211, P < .001). Plasma miR-204 levels were also negatively correlated with the glycosylated hemoglobin A_1c(HbA_1c) level (r = −0.702, P < .001), CACS (r = −0.710, P < .001), and the United Kingdom Prospective Diabetes Study (UKPDS) score (r = −0.355, P < .001). After multivariate logistic analyses, plasma miR-204 levels were still significantly and independently associated with the presence of CAC (odds ratio = 0.103, CI = 0.018-0.583, P < .001) after adjustment for conventional risk factors. Receiver operating characteristic curve analysis showed that plasma miR-204 levels can predict the severity and extent of CAC, and the specificity was higher than that of the traditional risk factors UKPDS score and HbA_1c. In conclusion, the downregulation of miR-204 was independently associated with CAC in patients with T2DM.