This dataset supports the manuscript titled “ENHANCING DATA MANAGEMENT THROUGH OPEN DATA POLICIES: INVESTIGATING NIGERIAN UNIVERSITY LIBRARIES’ INSTITUTIONAL REPOSITORIES (IRs)”. The dataset contains responses collected from librarians managing the Nigerian university libraries IRs listed on OpenDOAR to evaluate the current state of data management practices within Institutional Repositories. The dataset provides evidence on three core areas of inquiry: 1. Data literacy of librarians measures the knowledge, skills, and competencies of librarians responsible for managing institutional repositories, including data handling, metadata standards, preservation, sharing, and reuse practices. 2. Challenges affecting open data implementation identifies institutional, technical, policy-related, and capacity-related barriers influencing data availability, data literacy, data utilisation, and the implementation of open data policies within university libraries. 3. Repository data index, data literacy and open data policy outcomes examines how repository-related data practices influence open data policy adoption. Due to a very high correlation between data availability and data utilisation (r = 0.948), the two constructs were merged into a single composite variable termed “Repository Data Index” to address multicollinearity and preserve their shared explanatory contribution. The dataset therefore includes variables for repository data index, data literacy, and impact of open data policy to facilitate regression analyse.