ObjectivesTo examine associations of movement behaviour compositions with health-related quality of life in children. MethodsBaseline data (2018) from the TransformUs study were used. Overall, 891 children aged 7–12 years [69% of consented sample] recorded valid accelerometry data (ActiGraph GT3X+; 4 days, including ≥1 weekend day). Time spent sedentary, and in light-, moderate-, and vigorous-intensity physical activity were extracted. Health-related quality of life was assessed using five EQ-5D-Y health-related quality of life dimensions (mobility, looking after myself, doing usual activities, having pain/discomfort, and feeling worried/sad/unhappy [all dichotomized as no versus any problems]) and one continuous scale assessing overall perceived health. Regression models examined associations between waking movement behaviour compositions, including longer and shorter sedentary (<5 and ≥ 5 min) and physical activity (<1 and ≥ 1 min) bouts, and health-related quality of life. ResultsThe waking movement behaviour composition was associated with overall perceived health (whole sample, and boys and girls separately, but high socio-economic status only) and having pain/discomfort. More relative time in shorter versus longer sedentary bouts was associated with lower overall perceived health and higher odds of pain/discomfort. More relative time in shorter versus longer light-intensity and moderate-intensity bouts, were associated with decreased and increased odds of pain/discomfort, respectively. Finally, more time in shorter versus longer vigorous-intensity physical activity bouts was associated with better perceived health. ConclusionsChildren's movement behaviours seem to be related to health-related quality of life. Longitudinal evidence from more diverse samples with 24-h wear protocols and context-specific measures are needed to better understand this association.