Adolescents and young adults (AYAs) recently diagnosed with cancer are medically vulnerable but little is known about vaccine uptake/intent in this group. AYAs reported on their COVID-19 vaccine uptake/intent. Logistic regression models examined factors associated with vaccine uptake. Higher education (adjusted odds ratio [aOR] = 1.9, 95% confidence interval [CI]: 1.0-3.5) and knowing someone diagnosed with COVID-19 (aOR = 7.2, 95% CI: 1.6-33.5) were associated with increased vaccine uptake. Prior personal diagnosis of COVID-19 (aOR = 0.1, 95% CI: 0.1-0.7) was associated with lower odds of uptake. Targeted interventions may be needed to improve uptake among this group. (ClinicalTrials.gov Identifier: NCT04585269).