Effective, interpersonal teacher–student relationships and positive rapport are widely known to positively impact student attainment and learning experiences. Establishing and maintaining these have been particularly challenging, however, since the Covid-19 pandemic forced higher education (HE) teaching online in 2020. This study, therefore, aimed to explore English for Academic Purposes (EAP) teachers’ experiences of building rapport with international students in online learning environments in UK HE institutions during emergency remote teaching via sequential explanatory mixed methods and three research questions. Study Phase 1 comprised a structured, online, quantitative and qualitative questionnaire completed by 36 participants of the target population from 19 UK HE institutions, while Phase 2 employed in-depth qualitative interviews with three selected participants from Phase 1. Three themes emerged as most significant when considering teacher experiences of building rapport with students online: online communication in online sessions; teacher–student communication outside online sessions; and teacher availability and accessibility. The findings suggest that if online sessions could primarily be used as opportunities to meet learning outcomes, then the necessary and conscious task of building teacher–student rapport might be more effective in frequent 1–1 tutorials with students or during any available pre- and post-online session time.