Background Obesity is a complex biopsychosocial condition that involves biological, behavioral, and sociocultural determinants, and growing evidence highlights the role of weight-related stigma in shaping emotional distress, health behaviors, and clinical outcomes. This study investigated the validity evidence of the Brazilian version of the Weight Self-Stigma Questionnaire (WSSQ), examining its internal structure and its associations with self-esteem, psychological distress, and body image.Methods A sample of 262 adults residing in the Central-West Brazil, aged between 18 and 72 years (M = 33.0; SD = 13.4), was predominantly female (72.9%). Among the participants, 58% self-identified as White, 52.5% were classified as overweight, and 47.5% as obese. Participants completed the WSSQ, BSQ, K10, RSES, and a sociodemographic questionnaire.Results Confirmatory factor analyses supported the two-factor model originally proposed, demonstrating superior fit, theoretical coherence, and satisfactory reliability indices. The bifactor model also presented adequate fit but showed weaker item representativeness. Convergent validity analyses revealed moderate to strong negative correlations with self-esteem and moderate to strong positive correlations with distress, anxiety, depression, and body dissatisfaction, replicating international findings and reinforcing the relevance of internalized self-stigma for psychological functioning.Conclusions The results provide robust evidence of validity and reliability for the Brazilian WSSQ and support its use in clinical and research contexts. The instrument may contribute to culturally sensitive assessments and to interventions that address the emotional and social dimensions of obesity, a phenomenon still understudied in the Brazilian context.