Productivity of administrative personnel is crucial to the effective functioning of public universities, yet limited empirical attention has been given to the ethical determinants of office managers’ productivity. This study examined the influence of work ethics on the productivity of office managers in public universities in Osun State, Nigeria. A quantitative research design was employed, covering office managers from Obafemi Awolowo University, Ile-Ife; Osun State University, Osogbo; the University of Ilesa, Ilesa; and the Federal University of Health Sciences, Ila-Orangun. Using a total enumeration sampling technique, data were collected from 262 office managers via a structured questionnaire measuring work ethics and productivity. Simple linear regression analysis tested the hypothesis at the 0.05 level of significance. The results revealed a statistically significant and positive influence of work ethics on productivity, F(1, 181) = 189.541, p < .005, accounting for 51.2% of the variance (R² = .512), with a strong positive correlation (r = .715). The regression model indicated that a unit increase in work ethics corresponded to an increase of 1.057 units in productivity (β = .715), demonstrating a large and practically meaningful effect. The findings indicate that high adherence to work ethics, particularly duty compliance and rule integrity, significantly enhances office managers’ productivity. These results support Deontological Ethics Theory, highlighting rule adherence and duty as central to ethical behaviour and sustained organizational performance. The study recommends that university management should strengthen ethical standards and institutional frameworks to maintain and further enhance office managers’ productivity.