Background: Child poverty has been gradually rising, and about 12% of all Norwegian children are living in a state of relative poverty. This study was part of the New Patterns project, which recruits low-income families requiring long-term welfare services. Included families receive integrated welfare services, with the help of a family coordinator. The current study objectives were to explore the associations between HRQoL, demographic variables (age, gender, immigration status) and leisure activities in children and adolescents in low-income families. Methods: A cross-sectional survey was conducted among low-income families. Participating families had children (N = 214) aged 8–18 years.The family had a household income below 60% of the equivalized median population income for three consecutive years and needed long-term welfare services. HRQoL was measured using the KIDSCREEN-27 self-report instrument. Descriptive statistics, including means, standard deviations, and proportions, were calculated, and ordinary least squares regressions were performed, clustering standard errors at the family level. Results: Compared with boys, girls reported lower HRQoL on only one out of five dimensions, physical wellbeing. In the regression analysis we found statistically significant positive associations between migrant status and HRQoL on all five dimensions: physical wellbeing, psychological wellbeing, parents and autonomy, peers and social support, and school environment. In addition, age was associated with school environment, and age, gender and participation in leisure activities was associated with better physical wellbeing. Conclusions: Baseline results regarding HRQoL among children and adolescents in low-income families indicate that they have overall good HRQoL, though some participants had low HRQoL scores, especially on the physical and social support dimensions. Children with an immigrant background report higher HRQoL than do children without an immigrant background.