Purpose: This study aims to determine the predictive strength of personality traits based on the five-factor theory on the level of career maturity Research Methods: The sample of the study included a total of 429 high school students, 248 females (57.8%) and 181 males (42.2%). The study utilized the "Career Maturity Scale" to determine the students' career maturity levels. To measure the personality traits of the students, the "Five-Factor Personality Traits Test" was used. Findings: Results showed that the personality trait variables included in the model altogether significantly predicted career maturity (R = 0.35, R[superscript 2] = 0.12, p<0.05). It has been observed that, in the model, independent variables explained 12% of the variance in career maturity. When the contribution of each independent variable to the model was analysed, the highest contribution came from neuroticism (ß = - 0.158), followed by extraversion (ß = 0.148), openness (ß = 0.109), agreeableness (ß = 0.090), and conscientiousness (ß = 0.083). Implications for Research and Practice: Findings of the study demonstrated that high school students should be encouraged to interact with people around them and access sources of information easily. Furthermore, their social skills should be enhanced to increase their career maturity levels. The ways to access resources to learn about various occupations, such as the Internet, magazines, and books, should be planned and presented for students, especially those with introverted and anxious personality traits.