BACKGROUND: Young adult cancer survivors are at risk for subsequent human papillomavirus (HPV)-related malignancies. High-risk sexual behavior increases risk for HPV acquisition; HPV vaccination protects against infection. We aimed to determine the prevalence of sexual behaviors, factors related to high-risk sexual behaviors, and the relationship between sexual behaviors and HPV vaccine non-initiation among survivors. METHODS: Survivors at comprehensive cancer centers, aged 18–26 years and 1–5 years post-treatment, reported sexual behaviors and HPV vaccine initiation (i.e., ≥1 dose). Multivariable logistic regression was performed to calculate odds ratios (OR) and 95% confidence intervals (95%CI) for factors associated with high-risk sexual behaviors (age at first intercourse