This study examines librarian’s professional ethics and reference service delivery in Colleges of Education in Delta and Edo States in south-south, Nigeria. To guide the study, three research questions and one hypothesis have been formulated. The study adopted the descriptive survey design. The purposive sampling technique has been employed in the selection of data while the instrument for data collection was the questionnaire. The reliability of the instrument was estimated using test-retest method and the coefficient of 0.88 was obtained. Simple frequency and percentage were used to analyse section A of the research instrument. Descriptive and inferential statistics such as frequency and mean distribution were used to analyse the research questions. The hypothesis was tested using Cronbach Alpha correlation coefficient method at 0.05 level of significance. The findings of the research showed that there is significant relationship between librarian’s professional ethics and reference service delivery in Colleges of Education in Delta and Edo States.