Purpose The role of happiness at work (HW) on mental health (MH) in the education sector in Indonesia has not been widely examined. Additionally, the inconsistent results of previous studies on the relationship between job satisfaction (JS) and MH have led to the uncertainty of JS being a mediator. This study aims to fill the gap in knowledge by examining the effect of HW and perceived organizational support (POS) on teachers’ MH, with JS as a mediator. Methods This research employed a quantitative approach with a cross-sectional study design, using partial least squares structural equation modeling with SmartPLS software. The research participants included 490 teachers in the Special Capital Region of Jakarta province. Results The results indicate that HW is the highest predictor of teachers’ MH, and POS is the highest predictor of JS. Another notable finding is that JS was found to have a positive but not significant effect on teachers’ MH. However, it did impact the failure of the mediation relationship of this research model, which did not align with previous studies’ findings. Conclusion Schools must pay attention to HW to improve teachers’ MH. Additionally, they should provide support to teachers to increase their JS, especially during the COVID-19 pandemic.