In 2018, nine-valent human papillomavirus (HPV) vaccine eligibility expanded to include adults aged 27 to 45. This study aimed to identify knowledge, attitudes, and beliefs (KABs) about HPV and HPV vaccination among newly eligible mid-adult men, for whom uptake in adolescence and younger adulthood remains suboptimal. We conducted six virtual focus groups ( N = 34 participants) with unvaccinated men aged 27 to 45 living in Southern California’s Inland Empire. Data were systematically analyzed to identify emergent themes using the rigorous and accelerated data reduction technique. The sample of men was diverse (79% Hispanic, non-Hispanic Black, Asian, or mixed race/ethnicity; 26% gay or bisexual) and captured participants from across the socioeconomic spectrum. Eighty-eight percent of participants had never received a provider recommendation to be vaccinated against HPV. Many had unanswered questions about HPV and HPV vaccination, could not recall any HPV-related cancers that affect men, and were unaware of their current eligibility for vaccination. Embarrassment and stigma surrounding vaccination against a sexually transmitted infection, concerns about vaccine side effects and safety, and preferences for preventing HPV via “safer sex” and monogamy were salient barriers to vaccination. Nevertheless, many men were eager to learn more about HPV vaccination and engage with health care providers around that topic. Interventions aimed at improving men’s knowledge, changing social norms, and supporting health providers to identify HPV vaccine-eligible patients may be especially fruitful for facilitating shared clinical decision-making between mid-adult men and their health care providers.