Background <p>The shortage of nurses is the global nursing industry’s problem; low professional identity is the main reason. As a reserve group of nurses, the professional identity of practicum nursing students influences the expansion and stability of the nursing workforce. Analysis of the factors and mechanisms influencing professional identity may provide essential guidance for managing and intervening in the nursing workforce. This study aimed to identify the positive predictors and pathways of professional identity of nursing students during their practicum.</p> Methods <p>A quantitative cross-sectional study was conducted using the demographics, the clinical learning environment scale, the Utrecht work engagement scale-student scale, the Chinese version of the stress-related growth scale: short form, and the professional identity scale. Data were obtained from 952 Clinical nursing students from three medical schools in Sichuan Province. Data were analyzed using SPSS 26.0 (IBM, Armonk, NY, USA) and PROCESS v3.3 (IBM, v26.0) in SPSS.</p> Results <p>The results showed that professional identity was positively related to the clinical learning environment (<i>r</i> = 0.407, <i>P</i> &lt; 0.01), learning involvement(<i>r</i> = 0.506, <i>P</i> &lt; 0.01), and stress-related growth(<i>r</i> = 0.455, <i>P</i> &lt; 0.01). Similarly, the clinical learning environment was positively correlated with learning involvement (<i>r</i> = 0.484, <i>P</i> &lt; 0.01) and stress-related growth (<i>r</i> = 0.546, <i>P</i> &lt; 0.01). Meanwhile, the Process version 3.3 plug-in SPSS 26 tested and confirmed the multiple mediating effects of learning involvement and stress-related growth on the clinical learning environment and professional identity; the total effect of the clinical learning environment on professional identity was 0.284[ Bootstrap 95% CI: 0.260,0.308], of which the direct effect value was 0.155[ Bootstrap 95% CI: 0.124,0.185], accounting for 54.58% of the total effect and the total indirect effect was 0.129[ Bootstrap 95% CI: 0.124,0.185], accounting for 45.42% of the total effect.</p> Conclusions <p>This study found that improving the nursing students’ clinical learning environment, including interpersonal relationships, working atmosphere, team culture, student participation, task orientation, innovation, and personalization, as well as increasing their learning engagement, leads them to achieve stress-related growth, which both conducive to enhancing their professional identity as nurses. More importantly, improving the clinical learning environment can not only increase the learning input of nursing students but also help them better obtain stress-related growth, thus enhancing their professional identity. Teaching institutions need to strengthen the investigation and guidance of teaching hospitals, especially the construction of the working atmosphere, task orientation, and humanistic construction of teaching hospitals et al., create a good practice environment; on the other hand, it is necessary to pay attention to and guide nursing students’ practice dynamically and consciously plan their learning and career growth, which may be more conducive to the promotion of nursing students’ professional identity, it is also conducive to the expansion of the nursing team and improve the quality of nursing care.</p>