Human papillomavirus (HPV) vaccines offer primary prevention of cervical cancer and protection against other HPV‐associated cancers. HPV vaccine coverage in the United States (U.S.) remains low, particularly among older adolescents/young adults, and the uninsured. We assessed awareness and knowledge of HPV disease, HPV‐related cancers, and HPV vaccines among working, uninsured adults. Data from the 2014 Health Information National Trends Survey (HINTS 4, Cycle 4) were used as a benchmark. Patients were surveyed in late 2014 at the Volunteers in Medicine free clinic in Duval County, Florida. Surveys contained validated measures of HPV disease and vaccine knowledge; HPV‐related cancer knowledge was also assessed. Two‐hundred and ninety‐six surveys were analyzable with an 84% participation rate. Half (50.3%) of participants had heard of HPV, and 32.1% had heard of the HPV vaccine; in HINTS, these estimates were 63.6% and 62.7%, respectively (both P < 0.0001). In adjusted models, high HPV disease knowledge was associated with white race and increased education; high vaccine knowledge was associated with white race, increased education, and female sex. Recognition of HPV as a causative agent was 43.9% for cervical, 9.1% for anal, and 11.1% for throat cancers. For all HPV‐associated cancers, participants had lower knowledge/recognition relative to HINTS. The uninsured, socioeconomically disadvantaged adults we surveyed were unaware of a ubiquitous virus that can cause cancer and the existence of a vaccine to protect against it. These findings point to settings and populations in which initiatives to promote HPV vaccination as a cancer prevention tool remain critical.