Objective: To evaluate the effect of virtual reality (VR) on dental anxiety, pain, and behaviour at different time points among children undergoing dental treatment under local anaesthesia. Material and Methods: This randomised, two-armed, within-subject, cross-over, placebo-controlled trial included 76 children. Eligible participants were treated in two dental visits using the following methods: with protective glasses only, without distraction (attention placebo-controlled - APC); and with the treatment condition (i.e., VR). Primary outcomes were dental anxiety and pain; secondary outcome was dental visit behaviour. Heart rate scores were recorded as an objective measure to evaluate dental anxiety and pain. Subjective measurements for each variable were also performed. Results: Significant reduction in dental pain and anxiety was observed in the VR group, according to the heart rate scores; however, no statistical differences were observed according to the self-reported measures. Decreased dental anxiety and pain were associated with the first visit sequence with VR. Dental pain and anxiety scores were lower during local anaesthesia in the VR group than in the APC group. Conclusion: Virtual reality significantly reduced pain and anxiety during local anaesthesia in children undergoing dental treatment; therefore, it may be recommended during dental treatment in school-age children.