Background: Body image concerns are a critical psychosocial issue during emerging adulthood, influencing identity formation, self?esteem, and mental health outcomes. Psychological well?being (PWB), as conceptualized in Ryff’s multidimensional model, provides a multidimensional framework for assessing optimal functioning across autonomy, environmental mastery, personal growth, positive relations, purpose in life, and self?acceptance. Aim: This study examined self?esteem as a mediator of the relationship between body image concerns and psychological well?being, while testing gender as a moderator of the body image → self?esteem pathway. Methods: Data were collected from 398 emerging adults (M age = 20.11, SD = 2.66; 56% female) using the Body Shape Questionnaire (BSQ), Rosenberg Self?Esteem Scale (RSE), and Psychological Well?Being Scales (PWB). Structural equation modeling (SEM) with product?term interaction was conducted in lavaan (R), with indirect effects estimated using bias?corrected bootstrapping (5,000 resamples). Results: BSQ scores negatively predicted self?esteem, and self?esteem positively predicted PWB. Self?esteem partially mediated the relationship between body image concerns and PWB, while gender significantly moderated the BSQ → self?esteem path. The indirect effect of body image concerns on PWB via self?esteem was stronger among females. Conclusion: Findings highlight self?esteem as a key mechanism linking body image to well?being and underscore the need for gender?sensitive interventions. Programs that reduce body image concerns and enhance self?esteem may serve as protective strategies for promoting psychological well?being in emerging adults.