In the present time, students learn mathematics in an active and meaningful way if technology is integrated into the instruction. This study explored how the use of GeoGebra-supported Technology-enhanced instruction (TEI) affects the hypothesis testing performance of Grade 11 STEM students at Diffun National High School. Using a quasi-experimental design, 89 STEM students were divided into two groups: one acted as an experimental group (GeoGebra Group) who were exposed to the Traditional teaching method combined with GeoGebra-supported TEI, and a control group (Traditional Group) who were taught using the Traditional teaching method only. The results revealed that after the intervention, both groups exhibited improved performance in hypothesis testing, but the GeoGebra group showed better performance as evidenced by the group’s significantly higher posttest scores and greater mean gain. A moderate impact on students’ learning outcomes was also shown, as indicated by the computed effect size (d = 0.517). In light of these findings, it is evident that incorporating GeoGebra in mathematics instruction can beneficially increase students’ understanding of hypothesis testing and support improved academic performance.