Professional self-esteem and job security perceptions of teachers are considered to be factors that increase their teaching performance and overall teaching quality. The purpose of this study is to investigate the relationship between teachers' professional self-esteem and job security perceptions in Turkey and to determine the impact of demographic characteristics on this relationship. In the study, the nested embedded mixed research method was preferred. For quantitative data, the professional self-esteem and job security level of 660 respondent teachers were compared in terms of demographic characteristics (gender, marital status, education level, union membership, staff type, age, and years of service). For qualitative data, a structured interview form was utilized to examine the views of 54 participants about their profession. Our study reveals the intricate dynamics between teachers' professional self-esteem and job security, emphasizing the role of gender, union membership, and career stage. The findings of the study revealed that female teachers demonstrated higher professional self-esteem, likely due to their emotional intelligence and communication skills. Un-ionized teachers reported greater professional self-esteem, suggesting the positive influence of unions in safeguarding teachers' rights. Contract teachers, aware of job insecurity, exhibited elevated professional self-esteem, indicating a drive for continuous skill development. Younger teachers (aged 21-30) displayed higher professional self-esteem, emphasizing their enthusiasm and adaptability. These findings underscore the complex interplay between self-esteem, job security, and external factors, with significant implications for teacher support and policymaking.