This study investigated how moral distress contributed to burnout and mental well-being among 1318 healthcare and care professionals in Sweden using cross-sectional survey data and partial least squares structural equation modeling. Moral distress significantly increased both exhaustion and disengagement, which in turn negatively impacted mental well-being. Mediation analyses confirmed that burnout processes mediated the relationship between moral distress and mental well-being. Job control buffered the moral distress-exhaustion link, while collegial support had no effect. Linear moderation by age was non-significant, but curvilinear analysis suggested that moral distress affects burnout differently across ages. Age-group comparisons revealed that professionals under 30 and over 60 were most vulnerable to moral distress-related burnout. These findings highlight the need for preventive, age-sensitive strategies and workplace interventions that reduce moral distress and strengthen protective resources. The Swedish version of the Moral Distress Scale was validated across healthcare and care groups.