With recent technological advancements, COIL has become an increasingly popular model of international exchange in higher education. This approach promotes virtual international collaboration, fosters foreign language/content learning, and enhances intercultural awareness via the pedagogical principles of co-developed learning/teaching practices, shared learning outcomes, and deep collaboration. This chapter showcases how COIL can be applied to internationalise teacher education through a core Master in Teaching English for Speakers of Other Languages (MATESOL) module jointly organised by a Hong Kong/UK university. The main goal of this module was to broaden student-teachers’ repertoire of TESOL methodological practices. Eighty-five student-teachers engaged in various micro-teaching-related activities through a shared collaborative online annotation platform, ‘Perusall’, Zoom, and other modes of web-based communication. They participated in webinars, co-planned/developed lessons and teaching/learning materials, provided peer feedback/support, and conducted micro-teaching throughout a 12-week period. Video-recorded lessons and collaborative annotations were used to promote self-/peer-reflections. This chapter discusses the programme design and student-teachers’ collaborative practices, benefits, and challenges based on the questionnaire and interview data. Our findings indicate the participants’ pedagogic, personal, and social gains throughout their collaboration with peers despite considerable challenges. The chapter highlights the importance of strategically combining synchronous/asynchronous approaches and proposes guiding principles for internationalising COIL programmes.