The integration of technology in English as a foreign language (EFL) education has catalyzed informal digital learning of English (IDLE). EFL teachers increasingly partake in IDLE for diverse reasons: enhancing language skills, broadening pedagogical methods, accessing professional growth, and pursuing personal interests, potentially boosting job engagement. Yet, scant attention has been paid to IDLE's impact on EFL teacher-related aspects like job engagement, technological pedagogical content knowledge, and digital competence. This research probes the link between IDLE and EFL teacher job engagement, exploring the mediating roles of technological pedagogical content knowledge and digital competence. 375 EFL teachers were selected via convenience sampling and invited to complete scales measuring IDLE, technological pedagogical content knowledge, digital competence, and job engagement. The results of structural equation modeling revealed that technological pedagogical content knowledge and digital competence strongly mediated the relationship between IDLE and job engagement among EFL teachers. Additionally, a significant positive correlation was found between IDLE and the EFL teachers' job engagement. Furthermore, the findings disclosed a substantial positive correlation between IDLE and the EFL teachers' technological pedagogical content knowledge and digital competence. The findings underscore that IDLE can be incorporated in EFL education to improve EFL teachers' efficiency.