Background <p>Previous findings have established a negative association between financial strain and mental health, although this kind of investigation among Nigerian university students is relatively scarce. However, the mechanism as well as the conditions among the associations have not received sufficient research attention in the literature. Therefore, this study investigated the link between financial strain and mental health as well as the mediating effect of subjective happiness in the association between financial strain and mental health among university students. The study also explored the moderated mediated role of gender in the relationship.</p> Methods <p>This cross-sectional study used self-report measures of the Mental Health Scale, Financial Strain Scale, and Subjective Happiness Scale for data collection. A total of 196 university students aged 18–29 (female = 51.5%; mean age = 21.11 ± 1.64&#xa0;years) participated in the study. Data were analysed with the Pearson Product Moment Correlation (PPMC) and Hayes PROCESS macro statistical tools.</p> Results <p>A negative predictive association was linked with financial strain and mental health among university students. Further, subjective happiness was found to statistically mediate the link between financial strain and mental health. Also, gender did not have conditional indirect effect on subjective happiness on mental health through subjective happiness.</p> Conclusion <p>The study concluded that financial strain negatively linked with mental health and subjective happiness was associated with a mediation pattern between financial strain and mental health with no moderating effect in the association. Intervention policies aimed at reducing financial strain as well as student’s wellbeing programs aimed at improving positive affect among university students should be tailored toward enhancing students’ mental health.</p>