Persistent human papillomavirus (HPV) infection is responsible for the majority of oropharyngeal and cervical cancers in the USA. Currently, HPV curricula within medical and dental schools are not standardized. As such, we implemented a brief online educational intervention to increase medical and dental trainees' knowledge of the HPV vaccine and the association between HPV and cancer. The objectives of this study were to (1) assess medical and dental trainees' baseline knowledge regarding HPV and HPV vaccine, (2) determine the willingness to recommend the HPV vaccine to patients, and (3) evaluate the impact of an online intervention on HPV-related knowledge. Medical and dental trainees from two large academic centers in the USA were asked to fill out an online pre-intervention questionnaire, followed by a 10-min HPV educational intervention based on the Center of Disease Control and Prevention (CDC) resources, and then a post-intervention questionnaire. There were 75 participants (67.4% females; median age 18-30 years). When asked about HPV-related cancer types, the correct response increased from 28.4% (pre-intervention) to 51.9% (post-intervention; p < 0.01). When asked about the prevalence of HPV infections, the correct response improved from 36 to 72% (p < 0.01). There was also a 25.2% improvement in identifying the correct HPV vaccination dosing schedule (p < 0.01). Eighty-seven percent of the participants mentioned that the online education improved their HPV knowledge, and 68.5% reported that they were more likely to recommend HPV vaccine after the online intervention. The proposed online educational intervention was effective at improving HPV-related cancer and HPV vaccine knowledge as well as attitudes towards vaccine recommendation among dental and medical trainees and could be implemented in medical and dental school curricula in the future.