The cardiometabolic risk associated with metabolically healthy obesity (MHO) remains the subject of debate. It is unclear whether MHO is a transient condition that affects subclinical atherosclerosis risk. In this study, we aimed to investigate the association of MHO and its transition over time with incident subclinical atherosclerosis.A prospective study was conducted with 6220 Chinese adults who were free of cardiovascular disease (CVD) at baseline. Obesity was defined as BMI 25.0kg/m2. Metabolic health was defined as an individual having fewer than two of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (NCEP ATP III) criteria for components of the metabolic syndrome (excluding waist circumference). Subclinical atherosclerosis was measured by brachial-ankle pulse wave velocity, pulse pressure and albuminuria, separately or combined. Participants were cross-classified by BMI categories and by metabolic health status and its transition during follow-up. Inverse probability weighted logistic regression models were used to estimate ORs and 95% CIs for subclinical atherosclerosis.The MHO phenotype accounted for 16.3% of the total population and 32.8% of the population with obesity at baseline. Baseline MHO was not significantly associated with incident subclinical atherosclerosis. During a follow-up period of 4.4years, 46.8% of individuals with MHO developed a metabolically unhealthy status. Those with transient MHO had an increased risk of composite subclinical atherosclerosis compared with those in the metabolically healthy non-obesity reference group (OR 2.52 [95% CI 1.89, 3.36]). A transition from metabolically unhealthy to healthy status was shown to decrease the outcome risk. The relationship between BMI and subclinical atherosclerosis was partly mediated by BP and plasma glucose.MHO is not a stable condition and transient MHO conferred an increased risk of subclinical atherosclerosis, the early stage of CVD. Hence, individuals may benefit from early behavioural or medical management in order to avoid a deterioration of metabolic status and prevent atherosclerosis and CVD.