The changing educational landscape in the global context and the increasing interconnectedness and interdependence of the world have placed unprecedented demands on teacher education programs in preparing teachers to educate for 21st century global citizenship in K-12 schools. To chart the course of preparing global educators for an interconnected world, the Faculty of Education at the University of Prince Edward Island (UPEI) and UNICEF Canada have collaboratively developed an undergraduate course, entitled Educating for Global Citizenship. It focuses on preparing educators to teach for 21st century global citizenship and has been integrated into UPEI’s teacher preparation program as a compulsory course. This paper is based on a three-year study examining teacher candidates' experiences in learning to educate for global citizenship, the changes of their perceptions on global citizenship education, and the challenges and achievements they experienced in educational practices. Findings from this study indicate the unique opportunities and challenges teachers face in learning to educate for global citizenship and suggest the necessity of integrating global citizenship education in teacher education programs through a holistic approach.