Populations that are more than just slightly overdue for breast, cervical and colorectal screening should likely be targeted for policy and practice interventions. We used provincial-level administrative data to describe the Ontario population who are screen-eligible for breast, cervical and colorectal cancers but overdue by at least five years. For each cancer screening type, we created three cohorts and a binary outcome: screened at least once in the previous five years or not, using March 31, 2017 as our index date. We conducted simple descriptive analyses as well as multivariable logistic regression, where age category, immigrant status, neighbourhood income quintile, region, urban/suburban/rural status, primary care model type, and healthcare utilization were included in the models. More than 20% of Ontarians eligible for each of breast, cervical and colorectal cancer screening respectively had no history of screening in the previous five years. In multivariable analyses, people were significantly more likely to have no recent screening history if they lived in lower-income neighbourhoods (e.g. adjusted odds ratio [95% confidence interval]: 0.59 [0.58–0.59] for cervical screening), were recent immigrants, did not have a primary care provider, had a provider who practiced in a traditional fee-for-service model. Despite the presence of three provincial organized screening programs, we have found that more than one-fifth of Ontarians who are eligible for each of breast, cervical and colorectal screening respectively have not been screened for five years or more. Ensuring that all Ontarians have access to high-quality primary care, may be crucial to increasing screening uptake.