Teacher agency occurs when teachers demonstrate a capacity to solve pedagogical and curriculum challenges. This article delves into how tertiary English teachers in Thailand practice their agency in response to the abrupt conversion to online teaching amid the COVID-19 pandemic. This study drew on teachers' responses to a questionnaire (n=162) and semi-structure interviews (n=3) to identify their positioning and agentic actions. The results suggest that teachers' positioning as being professionally responsible for students' learning outcomes remains intact, even though the situation restricted them from going beyond their fundamental responsibilities. From a pedagogical standpoint, teachers' agentic actions identified were endeavoring to create an interactive learning environment; implementing social media platforms to compensate for the loss of face-to-face communication; working with students to adjust their teaching practices; promoting autonomous learning; and incorporating formative assessment approaches. Teachers might find themselves struggling to achieve their pedagogical goals, but once they become familiar with the new learning environment and master suitable teaching methods, online learning can be a viable option for formal language education, even in the normal situation.