Role-play has been widely used as a communicative technique for enhancing learners’ speaking performance. However, classroom-based empirical evidence on its use with Vietnamese primary EFL learners remains limited. This quasi-experimental study examined the effects of role-play activities on Grade 4 learners’ speaking performance and explored their perceptions of this technique. The participants were 98 Grade 4 learners from four intact classes at a public primary school in An Giang Province, Vietnam. Two classes were assigned as the experimental group and received speaking instruction through role-play activities, while the other two classes formed the control group and followed conventional speaking instruction. Data were collected through pre- and post-speaking tests, a post-intervention questionnaire, and semi-structured interviews. The findings reveal that both groups improved their speaking performance after the intervention; however, the experimental group demonstrated significantly greater gains in speaking performance than the control group. Findings from the questionnaire and interviews indicate that learners generally held positive perceptions of role-play activities, particularly regarding motivation, confidence, vocabulary development, pronunciation practice, and peer interaction. The findings suggest that role-play, when appropriately designed and supported, can serve as an effective instructional technique for developing speaking performance in primary school English classrooms. Implications for task design, teacher support, and classroom management are also provided.