Recent research has unveiled the critical roles of self-efficacy and buoyancy in teachers' work engagement. However, there has been limited research on the intricate links between teacher self-efficacy, buoyancy and engagement in the online English as a foreign language (EFL) teaching context. To address the underexplored relationships among these variables, the current study adopted a quantitative approach to verify the direct and indirect paths from online EFL teacher self-efficacy to engagement via the mediating effect of teacher buoyancy. We invited 978 Chinese high school EFL teachers to take part in the current study and answer questions about their self-efficacy, buoyancy and work engagement. The results of the structural equation modelling indicate that teacher self-efficacy could directly and indirectly predict online EFL teacher work engagement via the mediation of teacher buoyancy. The results of this study shed light on ways of improving EFL teachers' online teaching experience and educational outcomes.