Background: Breast cancer remains a major public health problem among women globally and in Nigeria. Breast self-examination is a simple, low-cost, and accessible breast aware- -ness practice that may encourage early detect- -ion and prompt health-seeking. Student nur- -ses are expected to have adequate knowledge and good practice of BSE because of their future role as health educators. Aim: This study assessed the knowledge and practice of breast self-examination as a preventive measure of breast cancer among student nurses in Kogi State, Nigeria. Methods: A descriptive cross-sectional study was conducted among 320 student nurses in selected nursing institutions in Kogi State. Data were collected using a structured selfadministered questionnaire. The questionnaire assessed socio-demographic characteristics, knowledge of BSE, sources of information, practice of BSE, attitude, and perceived barriers. Data were analysed using descriptive statistics, chi-square test, and binary logistic regression. Statistical significance was set at p < 0.05. Results: Most respondents were female, 294 (91.9%), and the largest age group was 20–24 years, 178 (55.6%). Overall, 222 (69.4%) respondents had good knowledge of BSE, while 97 (30.3%) had moderate knowledge. Although 191 (59.7%) had ever practised BSE, only 96 (30.0%) practised it monthly. Good BSE practice was recorded among 111 (34.7%) respondents. Knowledge level was significantly associated with good BSE practice (χ² = 11.166, p = 0.004). Level of study was also significantly associated with BSE practice (χ² = 7.963, p = 0.019). Logistic regression showed that respondents with good knowledge were more likely to have good BSE practice (AOR = 2.18, 95% CI: 1.20– 3.98, p = 0.011). Conclusion: Student nurses in Kogi State had good knowledge of BSE, but regular and correct practice was low. The findings show a knowledge-practice gap and suggest the need for practical demonstration, repeated training, and reminder systems to improve BSE practice among student nurses.