The effect of peer evaluation inside project-based learning (PBL) systems on student learning and participation in undergraduate business courses in Middle Eastern universities is investigated in this paper. The study seeks to evaluate how important elements—Improved Critical Thinking, Engagement Level, Effectiveness of Peer Feedback, and Enhanced Problem-Solving—contribute to the general learning experience and participation of students. Data were gathered from 350 undergraduate business students spread around the GCC using a quantitative, cross-sectional survey form. The associations between the predictors—independent variables—and Overall Impact—dependent variable were investigated by means of multiple regression analysis. With Overall Impact (R2 = 0.386, p = 0.001), the results showed a statistically significant link between the predictors. Improved critical thinking had the biggest impact among the independent factors (β = 0.408, p = 0.001), followed by enhanced problem-solving, engagement level, and effectiveness of peer feedback, all of which made significant contributions. These findings support the need of peer assessment in improving in PBL environments critical thinking, participation, and problem-solving abilities. Finally, this paper emphasises how well peer evaluation inside PBL supports active learning, teamwork, and student involvement. The results have practical ramifications for legislators and teachers in developing organised peer assessment systems to improve learning results. Future studies should investigate qualitative and longitudinal methods to handle constraints including the cross-sectional design of this study and self-reported prejudices.