Background: Colorectal cancer screening program using a fecal immunochemical test aims to reduce morbidity and mortality through early detection. Although screening participation is free-of-charge, almost 40% of the invited individuals choose not to participate. To bring new insight into how non-participation can be identified and targeted, we examined the association between marital status and screening participation; with a focus on partner concordance in participation and sex differences. Methods: This nationwide cross-sectional study included all Danish citizens aged 50-74 years, who were invited to colorectal cancer screening between 2014 and 2017. Logistic regression analysis was used to estimate odds ratio (OR) of participation while adjusting for sociodemographic variables. Results: A total of 1 909 662 individuals were included in the analysis of which 62.7% participated in the screening program. Participation was highest among women. Stratified by marital status, screening participation was markedly lower in widowed (61.5%), divorced (54.8%) and single (47.3%), while participation reached 68.4% in married individuals. This corresponded to ORs of 0.59 (95% CI 0.58-0.59) for widowed, 0.56 (95% CI 0.55-0.56) for divorced and 0.47 (95% CI 0.47-0.48) for single, compared to married individuals. Individuals married to a participating partner were five times more likely to participate than married individuals with a non-participating partner, regardless of gender. Conclusions: Marital status was strongly associated with participation in colorectal cancer screening, and participation was even higher in married individuals with a participating partner. Future efforts to increase participation in colorectal cancer screening could potentially benefit from considering the role of partner concordance.