Improving paediatric bronchiectasis outcomes requires high-quality research containing endpoints that meet study objectives and are meaningful for parents/patients. We developed a core-outcome set (COS) incorporating parent/patients? perspectives. Methods: An international, multidisciplinary panel of specialists in paediatric and adult respiratory medicine, infectious disease, physiotherapy, primary care, nursing, radiology, methodology, patient advocacy and parents whose children had bronchiectasis was assembled. We undertook a systematic review from which the panel constructed an outcome list of 21 items and developed separate surveys for parents/patients (European Lung Foundation [ELF] and Panel member networks) and health professionals (European Respiratory Society members and global experts). The results were presented to the ELF patient advisory group and expert panel to achieve a consensus COS for paediatric bronchiectasis. Results: There were 562 survey respondents (361 health professionals; 201parent/patients). The three highest ranked outcomes were common to both groups (quality-of-life [QoL], exacerbations and hospitalisations). The consensus COS (QoL, symptoms, exacerbations, hospitalisations, lost days [school/work], adverse-events, lung function, burden of therapy) was based upon the top 10 outcomes chosen by parents/patients, the remaining were selected according to intervention and discovery type studies. Interpretation: This international, parent and patient-informed consensus paediatric bronchiectasis COS ensures studies have clinically meaningful outcomes that improve systematic reviews and GRADE-informed guidelines.