BackgroundThe turnover of newly graduated nurses is a severe challenge for healthcare systems, and so it is essential to identify its predictive factors. This study investigates whether professional commitment, career adaptability, career self-efficacy, anxiety, and depression levels before and after internship can predict the turnover intention of newly graduated nurses after one year of employment.MethodsIn a longitudinal study, 271 undergraduate nursing students recruited by convenience sampling were surveyed before internship (T1), after internship (T2), and after one year of employment (T3), with all surveys conducted on the Wenjuanxing survey platform (www.wjx.cn). Generalized linear models and restricted cubic spline models were used to explore possible linear and nonlinear relationships between turnover intention and the variables of interest.ResultsProfessional commitment both pre-internship (β = −0.060, p = 0.007, 95% CI [− 0.104, − 0.016]) and post-internship (β = −0.053, p = 0.015, 95% CI [− 0.096, − 0.010]) can negatively predict turnover intention. There is also a negative linear relationship between post-internship career self-efficacy and turnover intention (β = −0.308, p < 0.001, 95% CI [− 0.436, − 0.180]). In addition, professional commitment both pre-internship (adjusted R2 = 0.046, p = 0.004) and post-internship (adjusted R2 = 0.068, p < 0.001), career self-efficacy both pre-internship (adjusted R2 = 0.039, p = 0.008) and post-internship (adjusted R2 = 0.116, p < 0.001), career adaptability both pre-internship (adjusted R2 = 0.057, p < 0.001) and post-internship (adjusted R2 = 0.039, p = 0.008), anxiety both pre-internship (adjusted R2 = 0.035, p = 0.014) and post-internship (adjusted R2 = 0.048, p = 0.003), and depression levels both pre-internship (adjusted R2 = 0.031, P nonlinear = 0.021) and post-internship (adjusted R2 = 0.053, p = 0.002) are nonlinearly associated with turnover intention.ConclusionsNursing educators and clinical care administrators must take action to enhance the professional commitment and career self-efficacy of nursing students during their internship. It is also important to pay attention to their career adaptability, as well as to any anxiety or depression that they may experience during clinical practice. This can help to reduce the turnover intention during the first year of their nursing career.