Collaborative writing was deeply rooted in Lev Vygotsky's sociocultural theory, where social interaction and communication were crucial for learning and cognitive development. Research on collaborative writing has been well-established in the mainstream education of English-speaking countries, however, it has been rarely conducted in the context of second language speakers. In Malaysia, the advancement of education technology has prompted local researchers to explore the practice of web-based collaborative writing activities. However, most local research on web-based collaborative writing has centered on students' acceptance and perceptions of the method. Teachers, despite playing a crucial role in facilitating and moderating students' collaborative writing, have rarely been the focus of these efforts. To minimize this information gap, this study employed a qualitative research approach with the aim of exploring ESL teachers' perceptions of web-based collaborative writing in Malaysian secondary schools. Based on interviews with six experienced and novice ESL teachers in Malaysia, this study discovered that collaborative writing was not well understood among secondary school teachers, particularly senior teachers and those located in rural areas. The findings of this study revealed that web-based collaborative writing in secondary schools was conducted on a smaller scale to suit students' levels of English proficiency. Teachers compensated for their lack of knowledge on the tools by allowing students the freedom to choose any web-based tools and platforms they prefer. The freedom of being in charge of their writing and the support students received throughout all stages of writing was theorized to increase students' creativity and interest in writing. Although the results of this study was based on the perceptions of a small sample, they offered various insights into possible teaching strategies, limitations, and benefits of collaborative writing that are beneficial to ESL teachers in Malaysia, as well as internationally.