This study assessed the associations between microalbuminuria in asymptomatic patients with type 2 diabetes and the presence, extent, and severity of coronary atherosclerosis, as measured by coronary computed tomography angiography (CCTA), and the long-term clinical outcomes. In total, the study enrolled 284 consecutive eligible asymptomatic patients with type 2 diabetes and without known coronary artery disease (CAD), who then underwent CCTA and 24 h urine albumin measurements. Microalbuminuria was defined as 30–300 mg/day urinary albumin excretion. Obstructive CAD, as measured by CCTA, was defined as maximum intra-luminal stenosis ≥50 %. Patients with and without microalbuminuria were compared in terms of obstructive CAD prevalence, and the extent and severity of coronary atherosclerosis. They were evaluated using the following data: coronary artery calcium score (CACS), atheroma burden obstructive score (ABOS), segment involvement score (SIS) and segment stenosis score (SSS). All-cause mortality within a follow-up period of 5 years was also compared. Compared to patients without microalbuminuria, patients with microalbuminuria were more likely to have obstructive CAD (p = 0.004). Microalbuminuria was associated with higher ABOS (p = 0.010), SIS (p = 0.029), and SSS (p = 0.011), except for CACS (p = 0.058). Multivariable analyses adjusted for conventional cardiovascular risk factors revealed that microalbuminuria was an independent predictor of obstructive CAD [odds ratio 2.255, confidence intervals (CI) 1.121–4.538, p = 0.023] and all-cause mortality (hazard ratio 3.469, CI 1.319–9.121, p = 0.012). In asymptomatic patients with type 2 diabetes, microalbuminuria was associated with increased risk of CAD and poorer clinical outcomes.