GeoGebra is an open-source software package for supporting mathematics teaching and learning. It enables a dynamic visualization approach that is beneficial for students' mathematics learning. However, few studies comprehensively investigate the effectiveness of GeoGebra as a scaffolding tool to achieve dynamic visualization in mathematics since its release. To fill this gap, we carried out a meta-analysis of studies examining the use of GeoGebra software for students' mathematics achievement since it was initially published in 2002 until 2022. Nineteen effect sizes were synthesized from fourteen studies in the last two decades, with a total of 1,334 participants. The analysis results demonstrated a positive medium-to-large effect (Hedges's g = 0.653) of GeoGebra as a dynamic visualization tool for improving students' mathematics achievement. Topic, treatment duration, and sample size were significant moderators of the effect size, suggesting that GeoGebra as a scaffolding for dynamic visualization is more effective when implemented with fewer participants (i.e. less than 50), for a short period (i.e. within four weeks), and in the topics of calculus and geometry than other conditions. Location, grade level, publication year, learning theory, group work, and student operation did not show significant moderating effects. Pedagogical implications of the findings for students, teachers, and educational researchers and practitioners are discussed.