Aim: This study aimed to assess the effect of iron deficiency on parent-reported changes in quality of life (QOL) among children receiving an adenotonsillectomy for paediatric obstructive sleep apnoea (OSA). Methods: This was a retrospective review study that recruited children under 16 years of age undergoing an adenotonsillectomy, adenoidectomy, or tonsillectomy for clinically diagnosed paediatric OSA between June 2020 and January 2021 inclusive, in Western Australia. The main outcome measures for this study were changes in QOL by age group and iron status, defined by an absolute change of more than 3 points on OSA-18 survey domains. Results: About 249 participants had iron studies performed on perioperative blood samples drawn at operation and completed both pre-operative and post-operative OSA-18 QOL questionnaires at initial consultation and 8–12 weeks post-surgery, respectively. 41.8% were iron deficient, 53.8% were borderline iron deficient and 4.4% had normal iron levels. Following surgery, a decrease was observed for all OSA-18 score domains in post-operation scores compared to pre-operation scores in both iron-deficient and borderline iron-deficient cohorts. ‘Daytime Problems’ in the <2 years group, within the iron-deficient cohort, was the only domain that found to be non-superior (i.e. ‘not better’) following surgery. Conclusions: Following adenotonsillectomy, patients with paediatric OSA reported significant improvements in QOL regardless of their iron status. Those undergoing an adenotonsillectomy for paediatric OSA had a high prevalence of iron deficiency at operation, especially those under 6 years of age.