This qualitative study, grounded in the sociocultural perspective, attempts to explore a Korean English teacher’s identity construction by employing a self-study, through narrative inquiry. As a self-study, the participant, Sofia, will also be the researcher. Data from her teacher life story narrative and reflective journals were analyzed to see how she reconstructs her identity through reflection of her own experiences. The study revealed four major themes showing the identity formation of the participant: (1) identity formation by resisting identity assumptions or stereotypes; (2) identity formation through influence of context; (3) identity formation through previous learning experiences; and (4) identity formation through conceptualizing teacher as professional. Based on these findings, the present study generates implications for teacher education practice and future research.