The study analyzed the relationships between high school students' career maturity, career decision-making difficulties, and career decision-making self-efficacy and aimed to investigate whether career maturity, career decision-making difficulties and career decision-making self-efficacy altered according to gender, type of school, and grade level. The study sample was composed of 665 high school students attending five different high schools in Bursa. The data collection tools included the Career Decision-making Difficulties Questionnaire, the Career Maturity Scale, and the Career Decision-Making Self-Efficacy Scale. Among quantitative research methods, a correlation model was applied. The analysis results revealed a weak but significant negative relationship between career maturity and career decision-making difficulties scale in terms of total scores and subscale scores. Additionally, there was a medium- and low-level significant negative relationship between the career decision-making difficulties scale total and subscale scores, and the career decision-making self-efficacy total and subscale scores. The subsequent analysis to describe the mediating role of career decision-making self-efficacy demonstrated that career decision-making self-efficacy had a partial mediating role. Furthermore, male students were found to have a more disadvantaged status than did female students in terms of career maturity. Based on the fact that students' career decision-making difficulties stemmed from the aspect of a lack of readiness, psycho education programs can be organized to determine the reasons for the lack of lack of readiness, find solutions, and provide the necessary information and skills. Future studies may focus on examining the reasons for the career maturity level differences.