This research article reports on instructional leadership as a controlling function in secondary schools. All the 41 secondary schools in Rangwe Sub County were included in the study and the targeted respondents were teachers and principals. A purposive sampling method was used to select the respondents from each school. A principal self-rating questionnaire, a teacher perception questionnaire, and a document analysis checklist were used for data collection. The collected data was analyzed using descriptive statistics, independent samples T-test, and regression analysis test. The study found that school principals engaged their deputies, heads of department, and directors of studies to conduct their day-to-day instructions in their schools. It was also revealed that classroom visits and observation of teaching and learning significantly influence student learning outcomes in secondary schools. The study concluded that involving the expertise of immediate juniors in day-to-day instructions is an effective way of implementing instructional leadership roles of the school principals in secondary schools. The study, therefore, advocates for the school principal becoming the overall instructional supervisor and instructional improvement catalyst.