Children often experience distressing medical procedures that can lead to pain and anxiety. Immersive virtual reality (VR) can alleviate procedural pain and anxiety in pediatric patients. This study aimed to investigate the effect of immersion on procedural pain and anxiety and whether anxiety sensitivity moderated this relationship. 128 pediatric patients ranging from 10 to 21 years of age were enrolled in the study, and they were randomly assigned to one of two conditions: VR plus standard of care or standard of care only during a painful medical procedure. The results showed that patients reported level of immersion significantly affects post-procedural anxiety scores, and anxiety sensitivity moderates this relationship. However, the study did not find significant effects of the patient's reported level of immersion on post-procedural pain scores, and anxiety sensitivity did not moderate this relationship. The study highlights the potential benefits immersive VR as an adjunct to standard care for pediatric patients undergoing medical procedures, particularly for those with stronger negative reactions associated with anxiety.