Teachers’ motivation has become a critical issue in the field of education. Understandings of teachers’ motivation for a career choice, and motivation for staying in the profession can be useful for educators, policy makers, and school leaders in finding effective ways to sustain and improve teachers’ motivation. In order to achieve this objective, the current study examined Vietnamese university EFL teachers’ motivation and teachers' basic psychological need satisfaction through the lens of Self-Determination Theory. Data were collected from 104 survey questionnaires and 30 in-depth interviews completed by EFL teachers from 14 universities in Vietnam. Findings suggested that Vietnamese EFL university teachers could be simultaneously intrinsically and extrinsically motivated to become an EFL teacher, and to stay in EFL teaching. However, teachers’ intrinsic motivation was reported higher than the extrinsic motivation. Although teaching is not a well-paid profession in Vietnam, many teachers said that they were committed to teaching because of the intrinsic values of the profession. Moreover, relationships between teachers' intrinsic motivation for EFL teaching and the satisfaction of teachers' basic psychological needs were identified. Findings of the current study suggested that enhancing the satisfaction of teachers' basic psychological needs at work can result in a high level of teachers' intrinsic motivation and commitment to EFL teaching and. This supports the importance of teachers' basic psychological need satisfaction and intrinsic motivation in the quality of EFL teaching as well as teachers' well-being. The study is concluded with practical implications and future research suggestions.