The dishonest practices in the conduct of educational research in South-South region particularly, and Nigeria generally, has called for urgent intervention. This study assessed data management practices and educational research effectiveness of University Lecturers in South-South Nigeria. A sample of 602 lecturers that were accessible during data collection responded to two questionnaires (Data Management Practices Questionnaire – DMPQ and "Educational Research Effectiveness Questionnaire – EREQ). Multiple regression was employed in the analysis of data. Findings revealed amongst others that; data storage, (...) data security, data retrieval, data sharing, and data re-use jointly contributed to the total variance in educational research effectiveness in terms of proper citations by 56.25%, problem-solving by 22.14%, knowledge creation by 34.50%, and generation of testable data by 36.88%; and their composite influence on educational research effectiveness in terms of proper citations (F=152.25,p<.05), problem-solving (F=33.90,p<.05), knowledge creation (F=62.78,p<.05), and generation of testable data (F=69.65,p<.05), is statistically significant. Based on the findings of this study, it was recommended among others that, there should be an up-to-date database or data warehouse in Ministries of Education where researchers can easily access data in order to increase the quality of researches by eliminating the problems of data fabrication and falsification. This study contributes to the existing body of knowledge by addressing the gaps arising from the paucity of research literature on educational research effectiveness. This study shows how data management practices affects the quality of educational research output of university lecturers using empirical evidence from Nigeria. (shrink)