The intensity of student nurses' motivation toward a certain career can influence their behaviors for career choice and decision making. However, little is known about the career motivation among student nurses toward gerontological nursing and their influencing factors.The objectives of this study were to examine student nurses' career motivation toward gerontological nursing and to explore potential predictors using Bandura's reciprocal determinism.A longitudinal design was used in this study.A total of 305 student nurses were recruited from six hospitals in Shandong province, and they completed the questionnaires over three stages.Student nurses' career motivation toward gerontological nursing, geriatrics attitudes, aging anxiety, empathy, and clinical practice environment were measured using the motivation questionnaire, the Geriatrics Attitudes Scale, the Anxiety about Aging Scale, the Interpersonal Reactivity Index, and the clinical practice environment questionnaire, respectively. Measurements were performed at the first month, fourth month, and seventh month of student nurses' clinical practice. A series of Pearson correlation, multiple linear regression, and generalized estimating equations were applied to analyze the data.Among 305 student nurses, the mean scores for career motivation toward gerontological nursing over three stages were 66.11 (SD = 8.98), 67.55 (SD = 8.53) and 66.78 (SD = 9.51), sequentially. There were significant differences in scores for career motivation over time (P < 0.05) and the lowest score was observed at the first month. Geriatric attitudes, aging anxiety, empathy, clinical practice environment and stage of clinical practice were notable predictors of student nurses' career motivation toward gerontological nursing.Student nurses' career motivation toward gerontological nursing needs to be improved, especially at the first month of clinical practice. Targeted interventions should cultivate positive geriatric attitudes, relieve anxiety about aging, promote empathy, and enrich the clinical practice environment to improve student nurses' career motivation toward gerontological nursing.