This study analysed the multimodal interactive discourse of one English-medium instruction (EMI) lecturer to engage students in a digital environment. It examined the first live online class given to a group of international students living in different countries. A methodology based on the multimodal (inter)action analysis approach was followed to study how interaction unfolded and was promoted and managed. Results showed the complexity of classroom interaction in this digital environment, the importance of lecturer waiting time, the high modal density and functional diversity of the follow-up/feedback stage and the most frequent discourse functions expressed during the interaction. The results will be of interest to designers of EMI training courses concerned with student engagement in virtual settings. Some suggestions are given regarding the need to know how to foster EMI lecturers’ awareness of multimodal interactive discourse.