The study investigates the interplay among second language (L2) learners’ willingness to communicate (WTC), L2 self-confidence (L2SC), and academic self-concept (ASC) within a cohort of Vietnamese university students studying in the United Kingdom. Employing an explanatory sequential mixed-methods design, self-reported quantitative data were collected via validated survey instruments (n = 32 students), followed by semi-structured interviews with a purposive subsample (n = 5 students) to contextualise the findings. Results revealed that participants exhibited moderate levels of WTC and L2 self-confidence, alongside emerging academic self-concept. Significant positive correlations were observed between WTC and L2 self-confidence and between L2 self-confidence and academic self-concept; a weak, non-significant association was found between WTC and academic self-concept. Qualitative data corroborated these patterns, highlighting how learners’ communicative confidence was shaped by supportive environments and evolving self-perceptions. While self-comparisons and cultural expectations occasionally influenced students’ academic self-concept, most participants reported resilience and a commitment to communication development. The study contributes to the literature by integrating psychological and contextual variables influencing WTC, offering pedagogical implications for enhancing communicative competence among international English as a second language learners.