This study investigated college students' career maturity as a mediator of the effect of professional identity on academic achievement. The researchers developed a structural equation model and a research hypothesis using the Chinese college students' professional identity scale, career maturity scale, and academic achievement scale. After experts' revision and confirmatory analysis, the 3 scales had sufficient reliability, validity, and fit. The researchers distributed electronic questionnaires to students in 4 universities in Jilin Province, China, and participants responded using 5-point Likert-type scales. The researchers collected 1,104 valid questionnaires. According to the analysis, college students' professional identity is a positive predictor of their academic achievement, and career maturity partially mediates the influence of professional identity on academic achievement. Therefore, improving Chinese college students' professional identity may improve their academic achievement, and professional identity can have a positive effect on academic achievement through career maturity. University administrators and teachers should enhance the career maturity of college students and promote their professional development.