Background <p>Preceptorship is a crucial component of nursing education in the final year, as it facilitates the transition to being a registered nurse. Preceptors guide student nurses in the clinical area through supervision and development, typically employing a traditional model with multiple ward-based preceptors who focus on clinical skills. However, the role of the preceptors in shaping nursing students’ career adaptability and professional identity has been underemphasized. This study evaluated a strategy of embedding a supplemental role-model mentor that provided continuous, personalized guidance during the final year of clinical placement. This study explored the influence of a newly implemented double preceptorship model on nursing students’ career adaptability and professional identity.</p> Methods <p>This study employed a quasi-experimental design. This study was conducted at a top-tier hospital in Guangzhou, China, from July 2023 to May 2024. The research subjects were final-year nursing students undertaking clinical placement in the hospital. The intervention group (<i>n</i> = 39) received additional support from a supplemental role-model mentor for the entire final year, in addition to ward-based clinical preceptors in each ward area. The control group (<i>n</i> = 32) received the traditional preceptorship model. The differences between the two groups were evaluated using the Career Adaptability Scale and the Professional Identity Scale.</p> Results <p>At baseline, no significant differences were observed between the two groups. Following the intervention, the scores in the intervention group were significantly higher than those in the control group in both career adaptability and professional identity (all <i>p</i> &lt; 0.05). Within-group analyses revealed a significant increase in career adaptability from pre- to post-intervention in the intervention group (<i>p</i> &lt; 0.05), whereas no significant change was observed in the control group. For professional identity, subscale analysis indicated significant improvements across four dimensions (except social modelling) within the intervention group (all <i>p</i> &lt; 0.05).</p> Conclusion <p>The double preceptorship system, which embeds a supplemental role-model mentor in the final year of clinical placement for nursing students, appears to enhance career adaptability and professional identity, potentially leading to improved retention in the workplace after nursing education.</p>