Background: Large population-based studies investigating the risks of overall and specific cancers among patients with hidradenitis suppurativa (HS) are limited. Objectives: To assess the overall and specific cancer risks in patients with HS compared with the risks in patients without HS in the Republic of Korea. Methods: A nationwide population-based cohort study was conducted over a 2-year period from 2007.1.1 to 2008.12.31. Individuals in the control group who were never diagnosed with HS or cancer during the washout period were randomly extracted and matched by age, sex, index year, and insurance type at a case-control ratio of 1:8, and patients with newly diagnosed HS between 2009.1.1, and 2017.12.31 were included. Follow-up data on incident cancer from 2009.1.1 to 2018.12.31 were included. Results: In total, 22 468 patients with HS and 179 734 matched controls were included in the study. The adjusted hazard ratio (aHR) of overall cancer in patients with HS was 1.28 (95% CI,1.15-1.42). Patients with HS had significantly higher risk for Hodgkin lymphoma (aHR,5.08; 95% CI,1.21-21.36), oral cavity and pharyngeal cancer (aHR,3.10; 95% CI,1.60-6.02), central nervous system cancer (aHR,2.40; 95% CI,1.22-4.70), nonmelanoma skin cancer (HR,2.06; 95% CI,1.12-3.79), prostate cancer (aHR,2.05; 95% CI,1.30-3.24), and colorectal cancer (aHR,1.45; 95% CI,1.09-1.93). Conclusion: HS appeared to be associated with a significantly increased risk of overall cancer as well as several specific cancers.