COVID-19 triggered social restrictions worldwide including the shutdown of schools. Whereas research has documented the negative effects on parents' well-being, less is known about children's well-being during the pandemic. We investigated the well-being, emotions, and COVID-19-related attitudes of 87 Norwegian elementary children (42 boys, 45 girls; M[subscript age] = 9.66 years, SD = 1.77) and their mothers (M[subscript age] = 39.69 years; SD = 5.79) in June 2020. Children reported reduced well-being relative to European norms. In line with research on child well-being before the pandemic, living in a one-parent home was associated with lower child well-being and more negative emotions during the pandemic, and mother's well-being was related to child well-being. Concerning attitudes towards COVID-19-related restrictions, we found a positive relationship between child age and attitudes and between children's attitudes and well-being. Implications for protecting children from negative effects of the ongoing and future pandemics are discussed.