Background/Objectives: Virtual reality (VR) is increasingly used to reduce pain during pediatric needle procedures, but its effectiveness may vary by developmental stage and gender. This study evaluated whether immersive VR reduces venipuncture pain in children and adolescents and examined parent–patient agreement and gender-specific response patterns. Methods: A prospective nonrandomized clinical study was conducted within a hospital-based pediatric venipuncture service using an alternating 1:1 allocation sequence. Participants aged 4–18 years underwent venipuncture with either VR (n = 49) or standard care (n = 29). Procedural pain was measured using the Faces Pain Scale–Revised (FPS-R) with independent parent ratings. Analysis of covariance (ANCOVA) compared post-procedural FPS-R scores while adjusting for baseline pain. Exploratory age and gender-specific analyses were also performed. Results: VR led to a clear reduction in pain for children, even after adjusting for baseline scores (3.55 vs. 4.73; p = 0.003). Adolescents, however, reported similarly low pain in both groups (2.81 vs. 2.79; p = 0.60), and several mentioned that the PEGI 3 content felt too young for them, which likely limited how engaged they were. Among children, girls showed the most noticeable drop in pain, which matches the subgroup’s adjusted significance (p = 0.011). Parent–patient agreement was stronger in children (r ≈ 0.7–0.8) than in adolescents (r ≈ 0.4–0.5), and VR did not change this pattern. Most participants said they would choose VR again for future procedures. Conclusions: Immersive VR helped reduce venipuncture pain in children but had little effect in adolescents, underscoring the need for age-appropriate or more interactive VR content for older patients. Overall, these findings support using VR selectively as a distraction tool that fits the developmental needs of pediatric groups.