<p>Adolescents and young adults (AYAs) with cancer may be at risk of poor nutrition while experiencing unique barriers to consuming healthful diets. Additionally, AYA cancer survivors are at increased risk of second neoplasms and adverse health sequelae. In this scoping review, we examined usual dietary behavior, tested dietary interventions, interest in nutrition, food insecurity and other barriers to healthful nutrition, in AYA patients with cancer and cancer survivors. Keyword searches were conducted in PubMed, SCOPUS, and ClinicalTrials.gov. We found that few studies had assessed nutritional intake and dietary interventions in AYAs receiving active cancer treatment and those in post-treatment survivorship. Most extant studies focussed on survivors of childhood cancer who were in the AYA age range at the time of the study, which is different from those diagnosed as AYAs. The current limited research in this area suggests that AYA cancer survivors may not adhere to dietary guidelines, particularly for fruits and vegetables, dietary fiber, sugar, fat, and processed meats. Dietary interventions using individualized nutrition counseling have shown initial results in improving overall diet quality among AYA patients with cancer and cancer survivors. Nutritional counseling via telehealth or digital technologies may help inspire healthful behaviors in this population. However, barriers to a healthful diet, particularly financial toxicities, may impede AYAs’ progress toward practicing healthful dietary behaviors. Dietary interventions for AYA patients with cancer need to be tested in larger and more representative samples and the effects of dietary choices on the efficacy and safety of novel cancer therapies in AYAs with cancer need to be further examined.</p>