Background: Existing studies on health‑related quality of life (HRQoL) mainly covered single growth stages of child‑ood or adolescence and did not report on the trends in the relationships of HRQoL with sleep duration, physical activity, and screen time. This study aimed to establish the population norm of HRQoL in children and adolescents aged 6–17 years and examine the associations of screen time, sleep duration, and physical activity with HRQoL in this population. Methods: We conducted a large‑scale cross‑sectional population‑based survey study of Hong Kong children and adolescents aged 6 to 17 years. A representative sample of students were interviewed to assess their HRQoL using PedsQL and EQ‑5D‑Y‑5L. Multivariable homoscedastic Tobit regression with linear form or restricted cubic spline of predictors was used to analyze the associations between screen time, sleep duration, and HRQoL. Multiple imputation by chained equations was performed to deal with missing data. Results: A total of 7555 respondents (mean age 11.5, SD 3.2; 55.1% female) were sampled. Their EQ VAS scores, Ped‑ sQL physical summary scores, and psychosocial summary scores were positively correlated with sleep duration and moderate/vigorous activity but was negatively correlated with screen time. Conclusions: Children and adolescents who had longer exposure to screen, shorter sleep duration, and lower physi‑ cal activity levels appeared to have poorer HRQoL as assessed by PedsQL and EQ‑5D‑Y‑5L. Advice and guidance on screen time allocation for children and adolescents should be provided at the levels of school, community, and family.