The study investigated the relationship between instructional supervisory practices and teachers' role effectiveness in public secondary schools in Calabar South Local Government Area of Cross River State. Two null hypotheses were formulated to guide the study. Ex-post facto research design was adopted for the study. The population of the study comprises all public secondary school principals and teachers in the study area. There are a total of six (6) principals and four hundred and thirty-three (433) teachers. Simple random sampling technique was used to select one hundred and ninety-five (195) teachers from six (6) public secondary schools. A well structured questionnaire tagged "Instructional Supervisory Practices Questionnaire (ISPQ) and Teachers' Role Effectiveness Questionnaire (TREQ)" were used for data collection. The results of the analysis revealed that there was a significant positive relationship between instructional supervisory practice of classroom observation and teachers' role effectiveness. The result also revealed that, there was a significant positive relationship between instructional supervisory practice of checking of teachers' lesson notes and teachers' role effectiveness. It was concluded that a closer, regular and continuous instructional supervisory practice rather than snappy, unscheduled and partial supervision is what is urgently needed especially now that a lot of changes have been introduced into the school curriculum. It was recommended among others that Government through the Ministry of Education should organize training programmes for principals as well as teachers on the need for effective instructional supervision.