In the era of globalization, the role of teachers is evolving to encompass global competence, prompting the need for teacher training programs dedicated to enhancing and expanding this competence. To comprehend the effect of current training initiatives on teachers’ global competence and guide future design, a research synthesis was undertaken through meta-analysis. This comprehensive meta-analysis, incorporating 105 effect sizes from 37 independent studies, unveiled a moderate to large effect (g = 0.46) of training programs on teachers’ global competence. Notably, we found that the training effects varied across different domains of global competence, with a more pronounced impact on the development of teachers’ knowledge and skills compared to their attitudes. Our findings also indicated some differences and similarities between in-service and pre-service training programs. For in-service teachers, specific attributes of training programs (i.e., delivery by districts and support for ICT) were found to have more significant positive effects. For pre-service teachers, training with a professional guide and solid knowledge building (e.g., courses and workshops) was found to be more effective in fostering their global competence, indicating that establishing a knowledge base should not be undervalued for pre-service teachers. This meta-analysis proposes that teacher training programs can be improved by incorporating “stage-appropriate” learning experiences that enhance teachers’ global competence.