This qualitative study investigates English as Foreign Language (EFL) teachers' perceptions and practices of blended learning in a Vietnamese university and influencing factors. Data were collected from (i) interviews with 15 teachers, three institutional executives, and one executive of online service provider, (ii) observing the teachers' practice in face-to-face classes, and (iii) monitoring their activities on the LMS. Findings revealed that teachers have limited understandings and use of blended learning due to three primary influential factors: (i) the traditional teacher-centred pedagogy, (ii) institutional management and leadership styles, and (iii) fragmented knowledge of technological, pedagogical, and content knowledge (TPACK) for blended learning. To improve the take up and potential benefits of blended learning in EFL education in Vietnamese universities, this study proposes (i) a systematic understanding of blended learning concepts, (ii) a localised TPACK framework, and (iii) a model of teacher professional development program.