Purpose: This paper aims to investigate adolescent English as a foreign language (EFL) learners' digitally mediated multimodal compositions across different genres of writing. Design/methodology/approach: Three Korean high school students participated in the study and created multiple multimodal texts over the course of one academic semester. These texts and other materials were the basis for this study's qualitative case studies. Multiple sources of data (e.g. class observations, demographic surveys, interviews, field notes and students' artifacts) were collected. Drawing upon the inductive approach, a coding-oriented analysis was used for the collected data. In addition, a multimodal text analysis was conducted for the students' multimodal texts and their storyboards. Findings: The study participants' perceptions of multimodal composing practices seemed to be positively reshaped as a result of them creating multimodal texts. Some participants created multimodal products in phases (e.g. selecting or changing a topic, constructing a storyboard and editing). Especially, although the students' creative processes had a similarly fixed and linear flow from print-based writing to other modalities, their creative processes proved to be flexible, recursive and/or circular. Originality/value: This study contributes to the understanding of adolescent English language learners' multimodal composing practices in the EFL context, which has been underexplored in the literature. It also presents the students' perspectives on these practices. In short, it provides theoretical and methodological grounds for future L2 literacy researchers to conduct empirical studies on multimodal composing practices.