This research aims to examine the influence of the GeoGebra application on students' self-efficacy in learning Vector topics. Using an experimental method with a pretest-posttest one-group design, the study involves 30 students enrolled in the Mathematics 4 course. A self-efficacy questionnaire, consisting of 30 positive and negative statements, was administered before and after the instruction, which are rated using a Likert scale. Data analysis was performed using paired t-test with α = 95%. The research findings indicate that: (1) Prior to the instruction, students had an average self-efficacy score of 99,07, with 6 students classified as high, 19 as moderate, and 5 as low self-efficacy; (2) After the instruction, students obtained an average self-efficacy score of 97,4, with 8 students classified as high, 16 as moderate, and 6 as low self-efficacy. Based on the paired t-test, sig(2-tailed) value is 0,501, indicating that there is no significant difference in students' self-efficacy before and after the instruction using the GeoGebra application. Additionally, the results reveal that 9 students experienced an increase in their self-efficacy category, 14 students did not experience any change in their self-efficacy category, and 7 students experienced a decrease in their self-efficacy category.