Prior to joining the National Institute of Education, Icy Lee was a Professor in the Faculty of Education at The Chinese University of Hong Kong (CUHK), where she held the positions of Department Chair of Curriculum and Instruction from 2015 to 2021 and Associate Dean of the Faculty of Education from 2020 to 2023. During her time at CUHK, she also served as the Director of the Postgraduate Diploma in Education programme and the MA in English Language Teaching programme.

As a researcher, Icy has gained international recognition for her work in the field of second language writing, with a focus on classroom writing assessment, feedback, and writing teacher development. She has delivered over 200 talks, including invited and plenary conference presentations in Brunei, Hong Kong, Japan, Korea, Macau, Mainland China, New Zealand, Singapore, Spain, Taiwan, Thailand, and the USA. Her international refereed publications, numbering over 150 and comprising books, book chapters, and journal articles, have appeared in more than 20 academic journals, such as Assessing Writing, Journal of Second Language Writing, Language Teaching, Language Teaching Research, System, and TESOL Quarterly. Some of her publications are key academic readings in TESOL / Applied Linguistic programmes around the world. She has been honoured with a number of prestigious research-related awards – namely, the Journal of Second Language Writing Best Paper Award in 2008 and again in 2022, TESOL Award for an Outstanding Paper on NNEST Issues in 2013, and Research Excellence Award at CUHK in both 2011 and 2015. She served as Co-editor of the Journal of Second Language Writing and is currently Principal Associate Editor of The Asia-Pacific Education Researcher.

Icy brings extensive teaching experience to her work, having taught in diverse educational settings such as secondary schools and university-based teacher education programmes in Hong Kong, as well as ESL (English as a second language) courses in Canada. She also has teaching/professorial experience across the globe, having served as Visiting Professor at prestigious institutions such as the Ontario Institute for Studies in Education in Canada, Thammasat University in Thailand, and the University of the Basque Country in Spain. Throughout her career, Icy has exhibited a strong commitment to excellence in teaching and to the preparation of pre-service and in-service teachers. Her dedication to innovative and reflective practice has earned her several awards. At CUHK, where she was a faculty member, she was recognized three times with the Faculty Exemplary Teaching Award. Internationally, she was honoured with the TESOL Award for Excellence in Teaching from TESOL International Association in 2010. As a classroom teacher, Icy firmly believes that teachers should be material designers, and this philosophy is reflected in her work. In 1999, she was recognized by TESOL International Association with the TESOL Award for Excellence in the Development of Pedagogical Materials

At the heart of her teaching and research is Icy's commitment to integrating her Christian faith into her practice. She believes that through teaching, research supervision, and mentoring she can help her students demonstrate their best, just as God brings out the best in us. She organized the Christians in English Language Teaching (CELT) Conference at CUHK in 2012 and delivered a keynote speech at the 2014 CELT Conference in Taiwan. Her presentation, entitled "Living out the Christian faith in the writing classroom," underscored the importance of modelling Christian values while facilitating student learning in the writing classroom.