As Canadian provinces and territories prepare to transition to HPV-based primary screening for cervical cancer, failure to identify and address potential barriers to screening could hinder program implementation. We examined screening-eligible Canadians’ attitudes towards and knowledge of cervical screening. A nationally representative sample of screening-eligible Canadians (N = 3724) completed a web-based survey in the summer of 2022. Oversampling ensured that half of the sample were underscreened for cervical cancer (>3 years since previous screening or never screened). The participants completed validated scales of cervical cancer, HPV, and HPV test knowledge and HPV test and self-sampling attitudes and beliefs. Between-group differences (underscreened vs. adequately screened) were calculated for scales and items using independent sample t-tests or chi-square tests. The underscreened participants (n = 1871) demonstrated significantly lower knowledge of cervical cancer, HPV, and the HPV test. The adequately screened participants (n = 1853) scored higher on the Confidence and Worries subscales of the HPV Test Attitudes and Beliefs Scale. The underscreened participants scored higher on the Personal Barriers and Social Norms subscales. The underscreened participants also endorsed greater Autonomy conferred by self-sampling. Our findings suggest important differential patterns of knowledge, attitudes, and beliefs between the underscreened and adequately screened Canadians. These findings highlight the need to develop targeted communication strategies and promote patient-centered, tailored approaches in cervical screening programs.