This study examines the influence of school factors on students’ moral conduct in Colleges of Education in Southwest Nigeria, using the Theory of Planned Behaviour (TPB) as a theoretical framework. The research investigates how parental characteristics (social status, family size, educational qualification) and school-related factors (school type, safety, discipline, and student-staff relationships) shape students’ moral behaviour. The study population comprised 1,800 students from 12 Colleges of Education comprising federal, state and private institutions located across four South-Western states of Nigeria. A sample size of 1,254 was determined using Taro Yamane’s formula. Data were collected from a sample of college students and analysed using descriptive statistics, including frequency counts, percentages, and mean values, to address research questions. Inferential statistical methods, such as Pearson Product Moment Correlation (PPMC) and multiple rRegression, were applied to test hypotheses at a 0.05 level of significance. The findings indicate that student-staff relationships (β = 0.437, p < 0.01) and discipline practices (β = 0.104, p = 0.007) significantly impact students’ moral conduct. Conversely, school type and safety did not show statistically significant effects (p > 0.05). Collectively, these factors account for approximately 24.8% of the variance in students’ moral conduct. The study concludes that promoting positive student-staff relationships, and enforcing discipline, are crucial for promoting ethical behaviour among students. It is recommended that moral education should be incorporated into school curricula, strengthening discipline policies, and creating supportive environments aligned with societal values. These measures aim to cultivate morally upright individuals capable of contributing positively to society. This research offers valuable insights for educators, policymakers, and stakeholders seeking to enhance moral development in educational institutions.