A mother's cancer diagnosis may have consequences for all family members, particularly for children, since it makes a parent less physically and emotionally available, with effects on the relationship with the child and his/her development. The main aim of this study was to analyze children's psychological adjustment in the context of maternal cancer by considering factors related to the child (i.e., age and sex), the mother (psychological adjustment), and cancer (i.e., time elapsed from the diagnosis and current oncological treatment). Self-report questionnaires investigating mothers' parenting stress, depression, anxiety, and children's emotional and behavioral problems were administered to 124 mothers (mean age = 44.52 years; SD = 7.22) diagnosed with cancer. A hierarchical regression analysis highlighted that time since diagnosis and mothers' anxiety and parenting stress accounted for almost 44% of the variance of the children's difficulties. Maternal depression, current oncological treatment, and the child's age and sex were not statistically significant. Higher mothers' parenting stress and anxiety and a longer time elapsed since the first diagnosis predicted higher levels of children's emotional and behavioral problems. These findings highlight the need to identify precursors of childhood distress in the context of maternal cancer and to develop structured programs to support both mothers and children.