Strong observational evidence supports the association between obesity and cardiovascular events. In elderly high-risk subjects, the Mediterranean diet (MedDiet) was reported to counteract the adverse cardiovascular effects of adiposity. Whether this same attenuation is also present in younger subjects is not known. We prospectively examined the association between obesity and cardiovascular clinical events (myocardial infarction, stroke or cardiovascular death) after 10.9 years follow-up in 19,065 middle-aged men and women (average age 38 year) according to their adherence to the MedDiet (<6 points or ≥6 points in the Trichopoulou's Mediterranean Diet Score). We observed 152 incident cases of cardiovascular disease (CVD). An increased risk of CVD across categories of body mass index (BMI) was apparent if adherence to the MedDiet was low, with multivariable-adjusted hazard ratios (HRs): 1.44 (95% confidence interval: 0.93-2.25) for ≥25 - <30 kg/m² of BMI and 2.00 (1.04-3.83) for ≥30 kg/m² of BMI, compared to a BMI < 25 kg/m². In contrast, these estimates were 0.77 (0.35-1.67) and 1.15 (0.39-3.43) with good adherence to MedDiet. Better adherence to the MedDiet was associated with reduced CVD events (p for trend = 0.029). Our results suggest that the MedDiet could mitigate the harmful cardiovascular effect of overweight/obesity.