High school students often encounter a range of challenges related to adolescence, future career uncertainty, family expectations, and societal pressures to succeed and excel. Addressing these issues requires targeted psychological support, particularly in enhancing academic self-efficacy (SE) and reducing pessimistic tendencies -- two constructs that have received limited attention in previous research. The present study aimed to examine the effectiveness of a group counseling program grounded in cognitive behavioral therapy (CBT) in improving academic SE and reducing pessimism among academically challenged high school students. A quasi-experimental design was employed, involving 32 students who were identified based on low academic SE and high pessimism scores. Participants were randomly assigned to either an experimental group (n = 16), which received the CBT-based intervention, or a control group (n = 16), which did not. Findings revealed a statistically significant improvement in academic SE and a reduction in pessimism among students in the experimental group. Based on these results, the study recommends that educators implement supportive strategies to enhance students' confidence in their academic abilities, thereby fostering a stronger belief in their capacity for academic achievement both within and beyond the classroom.