Objective: ADHD may predispose to obesity, a metabolic syndrome component. Affective disorders are also associated with MetSyn and ADHD. This study examined whether ADHD confers any added risk of MetSyn and obesity-related associations in a large sample with varying stages of affective disorders. Method: Participants included 2,303 adults from the Netherlands Study of Depression and Anxiety. Three groups were compared (controls, those with depressive/anxiety disorders without ADHD; and those with depressive/anxiety disorders and ADHD) for presence of MetSyn risk factors, body mass index, and waist–hip ratio. ADHD symptoms were identified by using a T-score > 65 (Conners Adult ADHD Rating Scale). Results: Multivariable analyses were additionally adjusted for sociodemographic, lifestyle, health factors, and affective disorders. Analyses showed no significant association between MetSyn, obesity-related variables, and comorbid ADHD. High Inattention and Hyperactivity/Impulsivity symptoms were not associated with MetSyn. Conclusion: This study did not confirm that MetSyn and obesity-related parameters are increased in comorbid ADHD.