Burnout is a persistent, negative, work-related state which involves mental, emotional, or physical exhaustion. Teacher burnout has been a major concern in mainstream education in recent years. However, it has been less examined among EFL teachers. Therefore, this study adopted a mixed methods sequential design to fill the gap by (a) identifying some Iranian EFL teachers' burnout and motivation profiles, (b) examining the (possible) relationship between their burnout and motivation to teach, and (c) investigating motivational factors which would predict teacher burnout. To these ends, 115 EFL teachers from language schools in southwest Iran took part in this study. To collect the data, Maslach Burnout Inventory-Educators Survey, developed by Maslach and Jackson (1986), Motivation to Teach Questionnaire, developed by Soenens, Sierens, Vansteenkiste, Dochy, and Goossens (2012), and a follow-up semi-structured interview with 15 participants were employed. Descriptive statistics showed that the EFL teachers had low levels of burnout and were autonomously motivated in their teaching. Correlation analysis also revealed negative relationship between autonomous forms of motivation (i.e., intrinsic and identified) and burnout. Moreover, multiple regression analysis demonstrated that the autonomous forms of motivation and external regulation could be better predictors of EFL teachers' burnout. The qualitative data from the interviews provided further insight into the quantitative results and explained some person- and work-related factors in relation to teacher burnout. Some implications are finally provided for decision-makers in the area of EFL pedagogy to improve EFL teachers' autonomous motivation to reduce their burnout experience.