During the last decade, Norway has experienced a major increase in permanent poverty among children. Although income inequality among Norwegian families is ranked as the lowest in Europe, the capital city of Oslo is characterized by significant differences in income across and within city districts. This paper analyses the degree to which utilization of specialized mental health services among children and adolescents is influenced by low-income and geographical-income inequality. In particular, do these factors affect immigrant children differently than they do native children? The data include the total population of children and adolescents with a native or non-Western background residing in Oslo (N = 121,449), in addition to register data covering all contacts with specialized mental healthcare institutions during the years 2008–2011 (N = 446,440). Multivariate logistic regression and Poisson regression were applied to analyse variations in rates of mental health care utilization. Non-Western children had significantly lower rates of utilization than their native peers, with the exception of a small minority of children residing in city districts with high levels of income inequality. For native children, there appears to be an inverse relationship between living in an area of income inequality and mental healthcare utilization: living in city districts with high income inequality to some extent lowers the probability of having contact with mental healthcare services. The results are discussed, involving factors such as underutilization, ethnic density effects, and selection processes that influence who becomes poor.