Introduction The impact of the COVID-19 pandemic on education resulted in school closures and the forced implementation of virtual teaching and teleworking. This situation together with the diversity of social and economic contexts in schools, has emphasized inequality in access to quality education and increased stress and anxiety among teachers.

Objectives This study aims to explore the mental health of teachers forced to telework because of COVID-19 and analyze its relationship with sociodemographic, teacher-related and working conditions.

Methods The sample was 278 Chilean classroom teachers who teleworked more than 50% during the 2020 academic year. The dependent variable was mental health measured through the General Health Questionnaire (GHQ-12). The independent variables were sociodemographic, teacher-related and work conditions. The internal structure of the mental health construct was evaluated using the Rasch model. Crude (cOR) and adjusted odds ratios (aOR) were estimated using logistic regression models. The analyzes were stratified by years of teaching experience and sex.

Results A high prevalence of poor mental health was found in teachers (58%). Working in a private-subsidized school (aOR = 2.89; 95% CI: 1.16 - 7.22), working two or more unpaid overtime hours (aOR = 2.25; 95% CI: 1.11 - 4.59) and having sickness absence (aOR = 3.82; 95% CI: 1.53 - 9.58) were associated with poor mental health. Working 35 hours or more weekly among less experienced teachers (6–10 years: aOR = 0.07; 95% CI: 0.01 - 0.51) and being a tutor teacher among women (aOR = 0.48; 95% CI: 0.23 - 1.0) had a protective effect on mental health.

Conclusion This study contributes to the recognition of a high prevalence of poor mental health among Chilean teachers and its associated contextual and labour factors. Need for actions to improve the working conditions of teachers who telework are guaranteed to improve their mental health.