This article provides a conceptual analysis of the two domains of global citizenship education and adult education and learning, along with their similarities and differences. It begins by unpacking the ambiguous and contested concept of global citizenship education and proposing a critical vision of it, within a global social justice framework. Against this backdrop, the article argues for re-conceptualizing adult education and learning as global citizenship education, instead of considering the latter to be one of the key issues of the former. Their structural link is grounded in their common epistemological nature. The domains are interlocked to the extent that both (1) promote active citizenship skills, (2) strive towards equality and social justice on a global level and (3) adopt a values-based approach and promote transformative learning. In conclusion, an original 'Four-dimensions approach to adult education and learning as global citizenship education' conceptual model is advanced potentially to inform policymakers, practitioners and researchers. The model is made up of four basic components of adult education and learning as global citizenship education, namely: aims and scope (what for), contents and skills (what), processes and pedagogies (how), actors and learning environments (who).