Genetics in paediatric oncology is becoming increasingly important in diagnostics, treatment and follow-up care. Genetic testing may offer a possibility to stratify survivors follow-up care. However, survivors' and parents' preferences and needs for genetics-related services are largely unknown. This mixed-methods study assessed genetics-related information and service needs of survivors and parents. Six hundred and twenty-two participants (404 survivors: mean age: 26.27 years; 218 parents of survivors: mean age of child: 13.05 years) completed questionnaires. Eighty-seven participants (52 survivors; 35 parents) also completed in-depth telephone interviews. We analysed data using multivariable logistic regression and qualitative thematic analyses. Thirty-six of 50 families who were offered cancer-related genetic testing chose to undergo testing. Of those not offered testing, 11% of survivors and 7.6% of parents indicated that they believed it was 'likely/very likely' that the survivor had inherited a gene fault. Twenty-nine percent of survivors and 36% of parents endorsed access to a genetics specialist as important in their care. Survivors (40.9%) and parents (43.7%) indicated an unmet need for information about genetics and childhood cancer. Parents indicated a higher unmet need for information related to the survivors' future offspring than survivors (p < 0.001). Many survivors and parents have unmet needs for genetics-related services and information. Greater access to services and information might allow survivors at high risk for late effects to detect and prevent side effects early and improve medical outcomes. Addressing families' needs and preferences during survivorship may increase satisfaction with survivorship care.