Abstract Background and aims Although the importance of hypertension in patients with cancer is widely recognized, little is known about the risk of developing hypertension in patients with a history of cancer. Methods and results This retrospective observational cohort study analysed data from the JMDC Claims Database between 2005 and 2022, including 78 162 patients with a history of cancer and 3692 654 individuals without cancer. The primary endpoint was the incidence of hypertension. During a mean follow-up period of 1208 ± 966 days, 311 197 participants developed hypertension. The incidence of hypertension was 364.6 [95% confidence interval (CI) 357.0–372.2] per 10 000 person-years among those with a history of cancer, and 247.2 (95% CI 246.3–248.1) per 10 000 person-years in those without cancer. Individuals with a history of cancer had an elevated risk of developing hypertension, according to multivariable Cox regression analyses [hazard ratio (HR) 1.17, 95% CI 1.15–1.20]. Both cancer patients requiring active antineoplastic therapy (HR 2.01, 95% CI 1.85–2.20), and those who did not require active antineoplastic therapy (HR 1.14, 95% CI 1.12–1.17) had an increased risk of hypertension. A multitude of sensitivity analyses confirmed the robustness of the relationship between cancer and incident hypertension. Patients with certain types of cancer were found to have a higher risk of developing hypertension than those without cancer, with varying risks dependent on the type of cancer. Conclusion Our analysis of a nationwide epidemiological database revealed that individuals with a history of cancer have a higher risk of developing hypertension, and this finding applies to both cancer patients who require active antineoplastic therapy and those who do not.