Children may suffer knee injuries due to motor vehicle crashes, sports, and falls. Additionally, children can suffer from rheumatic, neurological, musculoskeletal, and neuromuscular disorders which restrict joint movement. These types of injuries and disorders often result in knee joint impairment, thereby affecting joint mobility. Understanding the range of motion (ROM) of the pediatric knee is vital in diagnosing, examining, and treating these injuries and disorders. This study was undertaken to establish normative values for passive (PROM) and active (AROM) range of motion of the pediatric knee and to examine the effects of anthropometric and demographic factors on knee joint ROM. Normative reference values for both passive and active knee ROM were established for 295 children in the United Arab Emirates (Arab and South Asian ethnicity). The subjects’ PROM averaged 131.2° (117.2°, 140.2°) for boys and 132.8° (120.9°, 140.3°) for girls. Similarly, the observed PROM for children was 132.2° (118.6°, 141.2°), versus 130.8° (119.9°, 139.3°) for adolescents. Conversely, the subjects’ AROM averaged 129.3° (118.8°, 137.9°) for boys and 130.5° (120.9°, 137.4°) for girls. The observed AROM averaged 130.2° (119.5°, 137.8°) for children and 128.6° (121.5°, 137.4°) for adolescents. Significant differences in knee ROM based on ethnicity were identified. Additionally, significant correlations were observed between anthropometric factors and knee joint ROM. The gender and age-based normative values established in this study can be used in medical and vehicle safety analyses of knee injuries sustained by children as well as in the evaluation of knee joint impairments due to rheumatic, neurological, musculoskeletal, and neuromuscular disorders, thereby improving the outcomes of knee injuries and the treatment of joint impairments in children.