Extant literature describes challenges faced by international students, including language deficiency, culture shock, and identity crises. However, few studies have investigated international students’ second language (L2) learning in non-Anglophone higher education institutions using English as the medium of instruction (EMI), where English is used inside the classroom, and other language(s) are used outside. In a multilingual world, how international students’ L2 learning is shaped by their identities and social contexts, as multiple languages interact, is worth investigation. This study reports the L2 learning experiences of international students in Macao. Using semi-structured interviews, the researchers examined 15 participants’ routes for and negotiation of L2 learning investment in Cantonese, English, Mandarin, and Portuguese. Three main findings emerged: (a) participants’ main L2 learning routes were language courses and daily communication, with more investment in English and Mandarin than in Cantonese and Portuguese; (b) participants were discouraged from investing in L2s other than English, as they used English in Macao, identifying as “foreigners” and “deficient speakers” of other languages; (c) languages competed for participants’ limited resources, with English and Mandarin prevailing as more beneficial for their futures. This paper provides a unique perspective on the global language ecology through international student sojourners in a multilingual context.