We examined the psychological burden associated with metabolic syndrome (MetSyn). We used comparable longitudinal data of older adults (≥50years) from the UK (English Longitudinal Study of Aging) and the US (Health and Retirement Study). We defined MetSyn based on biomarker assessments (e.g., blood pressure, impaired glycemic control). Using regression models, we tested a range of individual psychological outcomes (e.g., depressive symptoms) associated with MetSyn. We also examined whether these psychological outcomes may explain or moderate the link between MetSyn and non-communicable diseases (NCDs). MetSyn was associated cross-sectionally with a range of psychological outcomes, including depression, anxiety, loneliness, hopelessness, cynical hostility, social strain, negative affect and decreased positive affect, social support and purpose in life. There was no convincing evidence that psychological factors interacted with or explained (mediated) the relationship between MetSyn and increased risk of developing NCD over 10-year follow-ups. MetSyn and the psychological burden outcomes examined may have independent effects on NCD risk.