This study examined the relationship between technology utilization and teaching effectiveness among secondary school teachers in Southwest Nigeria. The study adopted a descriptive survey research design in order to obtain information from a large population and describe the existing relationship between the variables under investigation. A sample of 1,600 teachers was selected through a multistage sampling procedure from different public secondary schools across the region to ensure adequate representation. Data for the study were collected using a self-designed instrument titled Technology Utilization and Teaching Effectiveness Questionnaire (TUTEQ). The instrument was carefully structured to measure teachers’ level of technology use as well as their instructional effectiveness in the classroom. To ensure the consistency of the instrument, its reliability was determined using the test–retest method, which yielded a reliability coefficient of 0.86, indicating that the instrument was reliable for the study. The hypotheses formulated for the research were tested using the Pearson Product Moment Correlation (PPMC) at the 0.05 level of significance. The findings revealed a significant relationship between technology utilization and teaching effectiveness among secondary school teachers in Southwest Nigeria. The results also showed that teachers’ digital competence and the availability of technological facilities significantly correlate with teaching effectiveness. The study concluded that effective utilization of technology enhances teachers’ instructional effectiveness and improves educational outcomes in secondary schools. It was therefore recommended that the government should provide adequate technological infrastructure and continuous professional training for teachers to support effective integration of technology in teaching and learning.