This article reports on a study examining the extent to which pedagogical activities can affect students' cosmopolitan communicative competence (CCC) through online transnational encounters. A total of 58 students from a Hong Kong university and 25 students from an American university were divided into 25 transnational groups. They communicated with each other through Google Docs, sharing culturally rich texts, exchanging views on these texts, and discussing rhetorical and cultural preferences/differences. After analyzing 90,000-word communication transcripts, we found that most of the students demonstrated and developed their cosmopolitan dispositions, skills, and knowledge. Based on these findings, we discuss how the activity contributed to the students' CCC by addressing four dialectical relations: historicity-modernity, text-context, self-other, and universality-particularity. The participants were challenged to make seemingly culturally irrelevant texts relevant to the transnational peers by moving the (ancient) texts across time scales and sociocultural contexts. The online communication based on the culturally (ir)relevant texts was a valuable site for the learners to enhance understanding about self and other, and examine the intricacies between universal and particular norms, values, and beliefs. The four dialectical relations can function as a set of heuristics for practitioners and researchers to reframe digital English Language Teaching (ELT) practices from the perspective of cosmopolitanism.