This mixed-methods study aims to examine the mediating role of attitude toward English varieties in the relationship between Informal Digital Learning of English (IDLE) and perceptions of using English as an International Language (EIL) materials in pre-service English teachers. We collected and analyzed survey data from 434 Indonesian EFL pre-service teachers, using the Jamovi programme. Survey results showed that both receptive and productive IDLE activities had a significant impact on attitudes toward different forms of English, which in turn had a significant impact on views of using EIL resources. Individual interviews (n = 10) and stimulated recalls (n = 7) revealed that participation in IDLE activities (e.g. watching YouTube videos with different English accents and users) aided in maintaining a more positive attitude toward different varieties of English. As a result, pre-service EFL teachers became more open to using EIL materials, such as listening materials that employ different English accents. This study suggests that IDLE is an important factor in developing positive attitudes toward English varieties, an approach that may enable today's pre-service EFL teachers to become more open toward and tolerant of integrating EIL pedagogy into practice.