As higher education becomes more digitally mediated and internationally oriented, social media interaction has increasingly become a crucial way across linguistic and cultural boundaries. It functions as a space where interaction unfolds, and meanings are negotiated. To explore how it contributes to the development of intercultural digital communication competence, this study conducted a systematic literature review. Following a PRISMA-guided process, we identified 19 empirical studies published between 2015 and 2025 and evaluated them using the Mixed Methods Appraisal Tool (MMAT). The findings suggested that this competence develops through the combined influence of pragmatic resources, ongoing behavioral adjustment, and affective factors. Features of politeness strategies, stance-taking, and multimodal cues play a noticeable role in shaping interaction. The result showed that participation alone does not automatically lead to improvement, and structured support and opportunities for reflection also make a difference. These findings offered implications for communication training and digitally mediated learning in higher education.