Digital multimodal composing (DMC) allows students to mobilize a wide range of multimodal resources to make meaning. While studies in DMC tended to focus on language-learning contexts, few of them examine its use in content-based courses whereby students are proficient L2 users expected to demonstrate understanding of abstract concepts using DMC. Drawing on semi-structured interviews with English-major students who attended a writing course in an English-medium instruction university in Hong Kong, the study investigated how the students' view of DMC was transformed after exposure to DMC pedagogy. The study findings suggest that students developed an increased awareness of the affordances and constraints of (new media) writing, and they strategically bring in and bridge 'in-class' and 'out-of-class' digital practices. Students also reported on the opportunities and challenges of DMC pedagogy through reflecting on their DMC experiences. The study proposes suggestions for implementing DMC in diverse teaching and learning contexts.