OBJECTIVE To investigate whether perioperative calcium and 1,25 OH vitamin D supplementation (PCDS) influences the rates of postoperative hypocalcemia and length of stay (LOS) following pediatric thyroidectomy. METHODS Retrospective Cohort Review. METHODS Tertiary children's hospital. METHODS 94 patients who underwent completion or total thyroidectomy with or without concomitant neck dissection from 2010 to 2020 at a single institution were included. Patients with pre-existing hypocalcemia or preoperative vitamin D insufficiency were excluded. Rates of postoperative hypocalcemia and LOS were compared for patients receiving PCDS to those receiving no supplementation. RESULTS Thirty percent of patients with PCDS had documented postoperative hypocalcemia compared to 64% of patients without PCDS (p = 0.01). Patients with PCDS had a median LOS of 30 h compared to 36 h (p = 0.002). Multivariable analyses confirmed that patients with PCDS had lower odds of postoperative hypocalcemia (OR: 0.32, CI: 0.11, 0.89) and shorter LOS by 17 h (SE: 8, p = 0.04) after adjustment for confounders. CONCLUSIONS PCDS is associated with significantly lower risk of hypocalcemia and shorter LOS. Standardizing preoperative care for pediatric patients undergoing thyroidectomy may decrease variability and improve outcomes following surgery.