Undergraduate academic achievement serves as a vital measure of higher education standards. The impact of perceived social support on academic outcomes has gained considerable attention. Nevertheless, existing studies have shown varied results regarding its correlation with undergraduate achievement, and the moderating effects remain unclear. This research utilized a meta-analytic method to comprehensively assess the link between perceived social support, including its subtypes (teacher, peer, and parental support), and undergraduate academic achievement. It further explored how variables like gender, economic level, cultural background and academic achievement measurement type function as moderators. The analysis incorporated 27 studies, resulting in 41 distinct effect sizes across 31,019 undergraduate participants. The results indicated a positive but modest correlation between perceived social support and academic achievement, with teacher support having the strongest effect among subdimensions. Moreover, the moderating effects of contextual and demographic factors on the support-achievement relationship exhibited variations across different subdimensions of perceived social support. This study provides essential empirical evidence about the complex mechanisms linking perceived social support with academic outcomes, offering theoretical and practical guidance for educational policy and future research.