Objectives: In the study, the authors aimed to explore the relationship between self-compassion, assertiveness and job satisfaction among teachers. Specifically, they examined whether assertiveness mediated the relationship between self-compassion and job satisfaction, filling a gap in the existing research on teachers’ well-being. Material and Methods: A total of 208 teachers (192 women, 16 men) aged 24–64 years, with an average teaching experience of 21 years, participated in the study. The participants were recruited using snowball sampling. Self-compassion was measured with the Self-Compassion Scale (SCS), assertiveness with the Teacher Assertiveness Questionnaire, and job satisfaction with the Job Satisfaction Scale. Statistical analyses included descriptive statistics, Spearman’s correlation and mediation analysis using Process tool (model 4). Results: Self-compassion was positively correlated with both assertiveness (r = 0.21, p < 0.01) and job satisfaction (r = 0.18, p < 0.05). Assertiveness was also positively related to job satisfaction (r = 0.21, p < 0.01). Mediation analysis demonstrated a total mediating effect of assertiveness in the relationship between self-compassion and job satisfaction, with the model explaining 8.3% of the variance in job satisfaction. Conclusions: The findings suggest that selfcompassion promotes teachers’ assertiveness, which in turn increases job satisfaction. This highlights the importance of supporting self-compassion and assertiveness as resources protecting against occupational stress and burnout. However, the cross-sectional nature of the study limits causal inference, so future research should consider longitudinal models and different educational contexts. These findings provide practical insights for the design of interventions aimed at promoting teacher well-being. Int J Occup Med Environ Health. 2025;38(4)