This nationwide cross-sectional survey in Mongolia assessed parents’ and health workers’ attitudes toward HPV vaccination ahead of its mandatory introduction in 2024. Data from 3,057 parents and 416 health workers revealed 79% of parents and 50% of health workers hesitant to vaccinate due to concerns over safety, term effects, and side effects. Attitudes varied by geographic region, with trust in healthcare professionals being key to decision-making. The study highlights the impact of COVID-19 on declining vaccine confidence and underscores the need for evidence-based information and education. Findings inform targeted advocacy to address vaccine hesitancy and strengthen HPV program rollout.