In English as a Foreign Language (EFL) class, students often face challenges in developing speaking skills due to limited exposure to English outside the classroom. To address this issue, students engage in Informal Digital Learning of English (IDLE) through various digital platforms and technologies beyond formal instructional settings, with teachers playing a supportive role in guiding and sustaining these practices. This study aims to explore the types of IDLE activities that students engage in to support their speaking skills and to investigate how EFL teachers provide support to maintain students’ engagement in IDLE. Employing a qualitative narrative case study approach, this study involved three EFL teachers at a vocational high school in Indonesia. Data were collected through semi-structured interviews, narrative frameworks, and digital artifacts, and analyzed using an interactive model consisting of data condensation, data display, and conclusion drawing. The findings reveal that students engage in both receptive IDLE activities, such as watching videos, listening to audio, and reading English texts, and productive IDLE activities, including vlogging, digital speaking tasks, and online peer interactions. These activities contribute to improvements in students’ speaking skills, particularly in pronunciation, vocabulary, fluency, confidence, and willingness to speak. Furthermore, teachers support students’ engagement in IDLE through three main support strategies: affection support, capacity support, and behavior support. Affection support helps sustain motivation and reduce anxiety, capacity support assists students in developing digital and linguistic competencies, while behavior support promotes consistency, accountability, and reflective learning practices. Although IDLE occurs outside the classroom, continued teacher support is essential to ensure that these activities remain aligned with learning objectives and complement formal instruction. Overall, this study underscores the importance of EFL teachers’ supportive roles in maintaining students’ engagement in IDLE to foster the development of speaking skills.