This study examined the under-researched relationship between informal digital learning of English (IDLE) activities (receptive IDLE activities and productive IDLE activities), affective variables (grit, motivation, self-confidence and second language speaking anxiety) and willingness to communicate in a second language. Data (N = 183) were collected through a questionnaire from one state university in an English-as-a-foreign-language Indonesian context. The results showed that students' willingness to communicate correlated significantly with all of the IDLE activities and affective variables. However, only productive IDLE activities, grit, self-confidence, and motivation were identified as the significant predictors of students' willingness to communicate. Findings suggest that students' IDLE engagement and affective states play a significant role in a second language communication. In particular, pedagogical benefits of affective variables (e.g., grit, self-confidence, and motivation) and productive IDLE activities should be emphasised to facilitate students' willingness to communicate in a second language. These results will broaden current knowledge of IDLE and second language communication behaviour, which can contribute to bridging the interdisciplinary gap between computer assisted language learning, second language acquisition, and psychology.