BACKGROUND: Vaccination of teachers is recommended during the COVID-19 pandemic to reduce the risk of infection for themselves and their students, as well as to encourage their parents to get immunized. The present study investigated the mental health outcomes and associated factors among vaccinated and unvaccinated teachers against COVID-19 infection in Bangladesh. METHODS: A cross-sectional survey was conducted in Bangladesh from March 4 to September 9, 2021. The frequency of symptoms of psychological distress, depression, anxiety, stress, post-traumatic stress disorder (PTSD), insomnia, and fear was assessed using the Bangla versions of the GHQ-12, PHQ-2, GAD-2, PSS-4, PC-PTSD-5, ISI, and FCV-19S scales, respectively. RESULTS: A total of 1,527 Bangladeshi teachers completed the questionnaire, with 678 (44.4%) being vaccinated and 849 (55.6%) being unvaccinated. Compared with unvaccinated teachers, vaccinated teachers had a statistically significant lower prevalence of psychological distress (35.8 vs. 42.9%), depression (37.6 vs. 46.4%), anxiety (31.9 vs. 45.1%), stress (18.3 vs. 32.0%), PTSD (33.0 vs. 43.8%), insomnia (25.2 vs. 36.9%), and fear symptoms (23.3 vs. 29.6%). Among vaccinated teachers, participants with master's or lower degree levels had significantly higher symptoms of depression, stress, and fear than other education levels. Respondents with children had a significantly higher risk of depression, anxiety, stress, and fear symptoms than those who did not have children. Participants who lost family members, friends, or colleagues due to the COVID-19 pandemic had a significantly higher chance of experiencing symptoms of anxiety, PTSD, and fear than those who did not. On the other hand, unvaccinated male teachers were significantly associated with a higher risk of all mental health outcomes except psychological distress and PTSD symptoms compared to female teachers. Participants who were smokers had a significantly higher chance of anxiety, stress, and fear symptoms than non-smokers. Compared to participants with strong social support, those with poor social support had a higher risk of all mental health outcomes except PTSD symptoms. CONCLUSION: This study suggests emphasizing the vaccinated to unvaccinated teachers as soon as possible to control the infection and improve mental health outcomes. Vulnerable teachers also required special attention, health-related education, and psychological support.