This study aimed to explore the influence of case-based learning (CBL) on the clinical reasoning of new graduate occupational therapists. A quasi-experimental single-arm study with a convergent mixed methods approach was conducted. The intervention was the 10-week CBL program, which included (1) guidance and mentorship in clinical practice and (2) case reports and presentations. Quantitative data collection consisted of the self-assessment of clinical reasoning in occupational therapy (SA-CROT) and the professional identity scale (PI scale); paired t-tests were conducted (p <0.05). The qualitative data collection was through a questionnaire with one open-ended question and reflexive thematic analysis was performed. The quantitative analysis results indicated that the CBL program improved the total score of the SA-CROT (p = 0.001, effect size r = 0.65), and all four of the SA-CROT's subfactors indicated improvement with moderate to large changes. In addition, the PI scale's two subfactors improved. Qualitative analysis revealed that the CBL program was an experience of "learning multidimensional thought processes" and "learning skills to improve clinical reasoning themselves" for participants. This study's results provide information on the positive influence of CBL on the clinical reasoning of new graduate occupational therapists and highlight the integration of the CBL program into continuing education, the importance of supervisors' guidance and mentorship, and learners' reflection and verbalization of clinical practice.