Despite repeated calls for the integration of digital multimodal composing (DMC) into English as a foreign language (EFL) teaching, the effect of the pedagogical use of DMC has been rarely investigated in the EFL context. Even less is known about the effects of DMC on students' L2 writing development. This study aims to address this issue by investigating whether and to what extent DMC would influence Chinese EFL learners' L2 writing performance. To this end, DMC was implemented as a pedagogical intervention in an EFL course offered at a Chinese university. The experimental group (n = 66) was required to complete three multimodal projects and the control group (n = 30) was asked to write on the same topics but without completing any multimodal project. All the participants completed two writing tasks before and after the intervention (a pretest-posttest design). The results of the study showed that as compared with the control group, the experimental group displayed significant improvements in five aspects of L2 writing (i.e., text length, mean length per T-unit, task requirement, content, and comprehensibility). Implications for integrating DMC into L2 writing teaching were considered.