Although it has been well noted in TESOL that ethnic minority students often experience difficulties in mainstream English classrooms, whether and how such students can be empowered in their English learning remains underexplored. This article reports on a longitudinal case study of a Chinese ethnic minority student's participation in a digital multimodal composing (DMC) project and its pertinent impact on the student's investment in EFL learning. Data were gathered through semistructured interviews, classroom observations, informal conversations, written reflections, and student-authored multimodal videos. The study found that using DMC in mainstream English classrooms constitutes a promising empowering and culturally sustaining strategy for facilitating ethnic minority students' investment in English learning. Through DMC, the ethnic minority student not only gained access to peer support and a collaborative learning community that was underemphasized in traditional classes, but also learned to capitalize on her ethnic knowledge as essential cultural capital for in-class participation. Noting the empowering role of DMC in positive ethnic identity constructions of the minority student and the investment in English learning, this study calls for attention to the importance of multimodality and the relevant literacy practices in empowering ethnic minority students to cross the linguistic and digital divides in mainstream classrooms.