Objective: The transition from active cancer treatment to survivorship represents a period of uncertainty for youth and their families, but factors associated with adaptation during this period are understudied. We evaluated associations among cancer and treatment‐related variables, family factors (family functioning, caregiver health‐related quality of life [HRQL], and caregiver distress), and patient HRQL after treatment completion. We assessed the indirect effects of neurocognitive difficulties on youth HRQL through family factors. Methods: One hundred fifty‐four caregivers (of patients’ ages 0–18 years) and 52 youth (ages 7–18 years) completed questionnaires assessing family factors, neurocognitive difficulties, and HRQL for patients within 6 months following treatment completion. Electronic health records were reviewed for cancer and treatment‐related information. Bootstrapping analyses assessed whether neurocognitive function had indirect effects on HRQL through family factors. Results: Family factors were associated with self‐ and caregiver reports of children's HRQL. Controlling for demographic, cancer, and treatment covariates, caregiver reports of their child's neurocognitive difficulties had an indirect effect on their reports of child physical HRQL through family functioning. Caregiver reports of their child's neurocognitive difficulties indirectly related to caregiver reports of child psychosocial HRQL through family functioning and caregiver HRQL. Indirect effects for self‐reported neurocognitive difficulties and HRQL were not supported. Conclusions: Findings highlight the need for routine psychosocial screening for youth and caregiver reports of family adjustment and HRQL during the transition off treatment. Providers are encouraged to offer interventions matched to specific needs for families at risk for poor family functioning to improve patient outcomes as they transition off treatment.