To effectively tackle obesity, it is necessary to identify all specific socioeconomic factors which contribute to its development. We aimed to highlight the prevalence of adult overweight/obesity in European countries and investigate the association of various socioeconomic factors and their accumulative effect on overweight/obesity status. Cross-sectional data from the Feel4Diabetes study for 24,562 adults residing in low socioeconomic areas were collected, representing Belgium, Finland, Greece, Spain, Bulgaria, and Hungary. Socioeconomic Burden Score (SEBS) was created, accounting for unemployment, financial insecurity, and education ≤ 12 years. Data were analyzed using analysis of variance and logistic regression. In total, 19,063 adults with complete data were included (34.5% overweight and 15.8% obese). The highest overweight/obesity rates occurred in Greece (37.5%/17.8%) and Hungary (35.4%/19.7%). After adjusting for confounders, age of <45 years and female sex were inversely associated with overweight/obesity, while low educational level (≤12 years), unemployment, and financial insecurity were positively associated. The increase in SEBS (clustering of socioeconomic disadvantages) was associated with increased overweight/obesity likelihood. This association of SEBS scores with overweight/obesity was evident for males and females across all examined countries, excluding males in low-income countries (Bulgaria and Hungary), where the highest SEBS score was inversely associated with overweight/obesity. The clustering burden of socioeconomic disadvantages on overweight/obesity was found to be influenced by the countries’ economic state and sex.