The integration of Generative Artificial Intelligence (GenAI) in English Language Teaching (ELT) is still at an experimental stage, particularly in developing countries where technological access and pedagogical adaptation remain uneven. While global research on GenAI-enhanced language education is expanding, limited attention has been paid to how university-level English teachers in under-resourced Asia-Pacific contexts navigate and adapt to these emerging tools. This study addresses this gap by exploring how Bangladeshi university-level English teachers engage with GenAI to facilitate first-year writing instruction, infusing two theoretical frameworks: the Post Method pedagogy and the TPACK model. Using a qualitative design, structured individual interviews were conducted with ten university English instructors, experimenting with GenAI-assisted teaching for the first time. Thematic findings include: (i) teachers exercised agency by using GenAI as receptive, assistive, and collaborative tools to enhance writing instruction; (ii) GenAI-generated materials were customized to learners’ cognitive, linguistic, and cultural needs; (iii) GenAI supported reflective and adaptive teaching practices; (iv) it promoted learner autonomy and engagement through exemplars and formative feedback; and (v) challenges persisted, including limited GenAI literacy, inadequate institutional policy, unequal resources, and generational resistance. While integration remains experimental, these findings highlight the potential of GenAI to enrich ELT. By offering a “glocal” perspective, the study informs the sustainable, context-sensitive adoption of GenAI in language education, emphasizing pedagogical adaptability, ethical awareness, and institutional support. It underscores the need to bridge the gap between GenAI policies emerging from Global North contexts and their practical, context-sensitive implementation in the Global South, particularly within Asia-Pacific countries.