This quasi-experimental study investigated whether purposefully designed multimodal materials boost EFL learner engagement more than text-only materials over a 15-week semester with 122 Chinese undergraduates in four intact classes. The multimodal group received video clips, audio recordings, annotated texts, and interactive quizzes, whereas the control group received identical content through text alone. Pre-post test gains and a 14-item engagement questionnaire served as the dependent measures. The multimodal group outperformed the control group on learning outcomes (d = 1.05, an upper-bound estimate) and across all three engagement dimensions: behavioral (d = 0.84), cognitive (d = 0.74), and emotional (d = 0.50). These findings suggest that even modest technological investments, when guided by deliberate content-modality alignment, can produce practically meaningful improvements in how students engage with and learn from EFL instruction, although the single-instructor design limits the causal inference.