Collaborative reflection helps teachers make meaning of their professional selves. For this reason, the infusion of appreciative inquiry into collaborative reflection can strengthen the formation of teacher identity. This case study aimed to investigate how appreciative collaborative reflection catalyzed the configuration of EFL teachers' professional identities during a three-month offline teacher professional education program in Indonesia. Three EFL teachers attending the professional education program and belonging to the same group during the reflection activities took part in the current study. During the activities, the three participants showed an interpersonal bond within the group. Data in the form of narratives were obtained through a semi-structured focus group discussion with the participants. A thematic analysis was conducted to discover the data's emerging themes regarding the affordance of the reflection in accelerating teachers’ professional identity formation. The findings revealed that appreciative collaborative reflection catalyzed teachers' professional identity configuration through recollections of professional experiences, equal engagement and interconnectedness, and positivity. The data-led, personal, collaborative, and appreciative reflection fostered the cultivation of positive personal selves. It is necessary that identity-related reflections be incorporated into teacher professional development programs to help teachers cultivate and purify their professional calling.