The existing literature in TESOL has revealed the multilayered, dynamic, and situated nature of teacher identity, but how language teachers construct their identities during curriculum reforms receives relatively limited attention, particularly in the context of teaching English for specific purposes (ESP). Theoretically anchored by the notion of contradiction in activity theory, this study investigates an ESP teacher's identity transformation in a Chinese university. Drawing on data from semi-structured interviews, classroom observations, and artifacts (policy documents and course materials), the findings reveal that the participant constructed her identities including "a skiff drifting in the dark," "an optimistic warrior," and "a nonconformist" through the teaching reform mediated by the corporatized culture and accountability system in higher education. The process of identity transformation was accompanied by her identity-driven efforts to resolve various contradictions and seek the delicate equilibrium between her agency and object-oriented reform. The study offers practical recommendations on teacher development and curriculum reforms for both language teachers and other stakeholders (e.g., teacher educators and school leaders) in different educational contexts.