This study aims to contextualize a flipped learning environment for ESP learners at a faculty of pharmacy, considering learners' suggestions and the teacher-researcher's field notes and benefitting from the collaboratively problem-solving processes of action research. Thus, the study was designed as first-person action research, where the teacher-researcher collaborated with the 38 pharmacy students taking an EOP course in their third year of study at a university in Turkey. The flipped learning instruction was evaluated, firstly, during implementation via video-recording 12 weekly three-class-hour courses, collecting learners' reflective journals and keeping field notes; and secondly, after finishing the implementation by holding focus group interviews with the students. The data were analyzed by inductive content analysis. The findings of the study indicate that the flipped learning strategy ensured many advantages, including the efficient use of class time, differentiation and peer interaction as well as bringing adoption problems derived from teacher dependence and established learning habits. Conducting action research not only improved the teacher-researcher's relationships with the students but also contributed to her professional identity as an ESP practitioner. Considering the findings of the study, practical implications for professional practice as well as suggestions for further research were presented.