Teaching has always been an emotionally demanding profession, which involves tremendous emotional labour on the part of language teachers. This is particularly true for instructors of English as a foreign language (EFL) suddenly obliged to teach online during the COVID-19 pandemic. Drawing on the approach of autoethnographic self-study, this article reveals the first author's understanding and negotiation of complex emotions during her online teaching from February to May 2020 in Wuhan, the centre of the COVID-19 pandemic during that period. This study sheds light on a language teacher's complex emotional experiences in relation to technology, students and colleagues under the sudden shifts of teaching environment. It also explores how emotional regulation strategies are employed through undertaking emotional labour and observing/renegotiating emotional rules. The study exemplifies the importance of emotionally managed classrooms, and language teachers are advised to make deliberate and strategic efforts in channelling positive emotions into online teaching. The authors call for more attention to self-study as a viable and instrumental approach to facilitating language teachers' continuing development and enhancing their emotional reflexivity and well-being.