This study explores EFL preservice teachers’ perceptions and experiences in online mentoring, expected to promote flourishing and teacher resilience in teacher education. A qualitative research design was used to gain insights into preservice teachers’ experiences of resilience and flourishing. Data from interviews, e-survey questionnaires, and artifacts were collected from 23 preservice teachers majoring in English language education at a medium-sized national university in Korea. Among the participants, six were given in-depth interviews for a better understanding of the conception of flourishing and teacher resilience. Findings reveal that four themes of flourishing were identified by this study, contributing to research on teaching EFL learners and teacher education in TESOL. Moreover, teacher resilience was found in the interviews and e-surveys. This study suggests that more research should be conducted to examine the conception of teacher resilience and the function of flourishing in fostering positive attitudes among EFL preservice teachers to their teaching and learning.