The benefits of mobile learning for science education have been widely described; however, there is scarce evidence of its effect on student learning. This article presents a meta-analysis of 44 empirical studies to assess the effect of mobile learning on students' learning at K-12 levels. Moreover, the study considered the moderating effect of science field, education level, pedagogical approach, learning environment, and control treatment. The results indicate that mobile learning has a large effect (g=0.75) on students' learning. This effect is influenced by the science field, the pedagogical approach, the learning environment, and the control treatment, and not by the education level. The findings suggest that mobile learning produces the best results when the situated learning approach supports the educational intervention. Furthermore, semi-formal settings, such as museums and outdoor activities, performed better than formal settings inside classrooms or laboratories. The best results were obtained when comparing mobile learning with traditional lectures. Similarly, mobile learning showed the best results in environmental education and when implemented in primary education. Finally, mobile learning yields better results than traditional lectures, traditional pedagogical tools, and other multimedia resources. Therefore, it can be promoted as a pedagogical approach to foster quality education for all.