Background Workers supporting adults with intellectual disabilities (ID) experience significant stress in their essential role during COVID-19 due to the high risk of their clients contracting COVID-19 and having adverse outcomes. The purpose of the current study was to describe the attitudes of workers towards COVID-19 vaccination prior to vaccination rollout, with a view to informing strategies to promote vaccine uptake within this high-risk sector. Methods An online survey was sent via email to workers supporting adults with ID in Ontario, Canada, between January 21 and February 3, 2021 by agency leadership and union representatives. Results Three thousand and three hundred and seventy-one workers, representing approximately 11.2% of Ontario workers supporting adults with ID completed an online survey. Most reported that they were very likely (62%) or likely (20%) to get a COVID-19 vaccine (vaccination intent) although 18% reported they were less likely to do so (vaccination nonintent). Workers with vaccination nonintent were younger and were more likely to endorse the beliefs that (1) it will not benefit them or those around them, (2) it was not part of their job, (3) rapid development confers uncertainties and risks, and (4) they were scared of potential vaccine side effects. Conclusions There is need to address common misconceptions among workers supporting adults with ID to help activate them as vaccine advocates in the communities they serve. Partnered efforts between workers, unions and agency leadership with public health experts to address concerns are required.