Background: Developing self-regulated learning (SRL) in a teacher-centered curriculum is challenging. Previous studies indicate professional identity formation (PIF), or the formation of self-identity with internalized values and norms of professionalism, might improve SRL.We designed a PIF-oriented education format for hybrid problem-based learning (PBL) and tested its effectiveness on SRL in a mixed research method.Methods: A randomized controlled crossover trial was conducted using 112 pre-clinical year students at Jichi Medical University. In the six one-day PBL sessions, Groups A (n = 56, female 18, mean age 21.5y ± 0.7) and B (n = 56, female 11, mean age 21.7y ± 1.0) experienced PIF-oriented pre-PBL learning: Group A had three sessions in the first half, B in the second half. Between-group PIF and SRL levels were compared using Professional Identity Essay (PIE) and Motivated Strategies for Learning Questionnaire (MSLQ). A qualitative thematic analysis of potential reasons for PIF improvement was performed using the PIE description.Results: Two-level regression analyses showed moderate improvement of PIF stages over time (R2 = 0.069), regardless of intervention. PIF-oriented pre-PBL learning alone did not significantly improve PIE stages or MSLQ scores. Thematic analysis indicated that PIF-oriented pre-PBL learning helped students recognize realistic difficulties in clinical practice, and articulate professional image and values. However, encounters in extracurricular clinical settings had diverse and meaningful impacts on PIF.Conclusions: Limited effect of PIF-oriented pre-PBL learning on PIF and SRL indicate challenges in SRL-oriented education for pre-clinical year students within a teacher-centered hybrid PBL curriculum.