Background: The association between juvenile idiopathic arthritis (JIA) and thyroid disorders has been defined in adults and, less frequently, in children. Objective: The study's goal was to assess thyroid function and the prevalence of thyroid antibodies in patients with juvenile idiopathic arthritis, as well as their relationship to disease activity. Methods: This cross-sectional study included 50 children and adolescents with juvenile idiopathic arthritis. All patients underwent thyroid function tests (thyroid stimulating hormone, free thyroxine, and free triiodothyronine), anti-thyroglobulin and anti-peroxidase antibodies by enzyme-linked immunosorbent assays. Results: The study showed that 52% of the patients were males and 48% were females. Their median age value was 9 years old. Thyroid abnormalities were detected in 52% of JIA patients. Overt hypothyroidism was the most prevalent disorder [14 patients (28%)], followed by subclinical hypothyroidism [11 patients (22%)], and then subclinical hyperthyroidism [1 patient (2%)], while 24 patients (48%) were euthyroid. Thyroid antibodies showed a normal level in all patients. On comparing thyroid function tests among patients with active and inactive JIA, no statistically significant difference was observed in thyroid hormone levels. Conclusion: To reduce the risk of delayed or undiagnosed thyroid diseases, it is necessary to routinely screen for thyroid function abnormalities in children with juvenile idiopathic arthritis.