Introduction <p>The study aims to reach an expert consensus and rank the top outcome measures that health professionals could utilise to measure change in pain, function, fatigue, and quality of life (QoL) of children with hypermobility-associated conditions and chronic musculoskeletal lower limb pain.</p> Methods <p>A three-round modified Delphi survey was conducted between February and April 2024. In the first two rounds, experienced health professionals were invited to rate the importance of outcome measures assessing change over time in children (5&#xa0;years and older) with hypermobility and chronic musculoskeletal lower limb pain. Outcome measures were collated from the literature and participant suggestions and assigned to four domains: pain, function, fatigue, and QoL. A priori threshold of consensus was 70% or greater of participants rating an outcome measure as important or essential. In the third round, participants ranked the outcome measures that met consensus in order of importance.</p> Results <p>Overall, 44 health professionals, from 13 countries, participated. Retention rate from round one to round three was 85%. Nine outcome measures achieved consensus.</p> Conclusions <p>Reaching consensus on this core set of outcome measures to assess change over time represents a step toward the development of international guidelines for the management of children with hypermobility and lower limb pain.</p>