Aim: This study aimed to examine the relationship between anxiety, state anxiety, trait anxiety, marital quality, and mental well-being among married individuals aged 35 to 45 years. Method: Employing a cross-sectional, correlational design, the study utilised standardised self-report tools: the State-Trait Anxiety Inventory (STAI), Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS), and Quality of Marriage Index (QMI). Sample: The sample comprised 100 married individuals (49 males and 51 females) selected through purposive sampling from urban settings in Vashi and Thane area of Mumbai State. Statistical analyses, including Pearson’s correlation, moderation analysis using Hayes’ PROCESS macro (Model 5), and independent samples t-test, were conducted. Results: revealed a weak but statistically significant positive correlation between state anxiety and mental wellbeing (r = .208, p = .038), and a strong negative correlation between trait anxiety and mental wellbeing (r = –.540, p < .001). Marital quality displayed a statistically significant but extremely weak negative correlation with mental well-being (r = –.048, p = .036). This counterintuitive finding suggests that higher perceived marital satisfaction may coexist with role strain or hidden stressors, requiring cautious interpretation with mental well-being (r = –.048, p = .036). Notably, marital quality significantly moderated the relationship between state anxiety and mental well-being (p = .037) but did not moderate the link between trait anxiety and well-being. Additionally, Gender differences emerged, with males reporting moderately higher levels of mental well-being than females (p = .001, Cohen’s d = .670), underscoring the need to consider gendered expectations and sociocultural pressures in marital dynamics. (p = .001, Cohen’s d = .670). Conclusion: The study concludes that while marital quality can buffer the effects of situational anxiety, trait anxiety poses a persistent threat to mental health.