In the context of English as a lingua franca, successful communication increasingly depends on not only native-like accuracy but also speakers’ ability to negotiate meaning across cultural boundaries. While intercultural communicative competence (ICC) has been widely discussed in English as a Foreign Language (EFL) research, its role in shaping learners’ oral fluency and confidence remains underexplored and theoretically fragmented. This paper addresses this gap by examining how ICC functions as a mediating mechanism that links linguistic performance with psychological readiness in EFL speaking. It argues that ICC supports oral fluency by fostering interactional adaptability and pragmatic awareness and enhances speaking confidence by mitigating anxiety and promoting tolerance for ambiguity. Importantly, this paper contends that ICC should be reconceptualised not merely as a cultural dimension of language learning, but as a dynamic mediator that enables a reciprocal relationship between fluency development and confidence building. The discussion culminates in an integrative conceptual model illustrating the cyclical interplay among ICC, fluency and confidence. The paper concludes by highlighting pedagogical implications for EFL contexts such as Vietnam, where limited authentic exposure heightens the need for interculturally informed speaking instruction.