The incidence of venous thromboembolism (VTE) in cancer patients may have changed in the past decade, possibly due to novel cancer therapies, improved survival, and high-resolution imaging. Danish medical registries were used to identify 499 092 patients with a first-time cancer diagnosis between 1997 and 2017, who were matched to 1 497 276 comparison individuals without cancer from the general population. We computed cumulative incidences of VTE 6 and 12 months after the diagnosis/index date. Hazard ratios (HRs) were calculated using Cox regression. Risk factors were examined by computing subdistribution hazard ratios (SHRs) in a competing-risk analysis. Cumulative incidence of VTE 12 months after the cancer diagnosis/index date was 2.3% (95% confidence interval [CI], 2.2% to 2.3%) in the cancer cohort and 0.35% (95% CI, 0.34% to 0.36%) in the comparison cohort (HR, 8.5; 95% CI, 8.2-8.8). Important risk factors for cancer patients were prior VTE (SHR, 7.6; 95% CI, 7.2-8.0), distant metastasis (SHR, 3.2; 95% CI, 2.9-3.4), and use of chemotherapy (SHR, 3.4; 95% CI, 3.1-3.7), protein kinase inhibitors (SHR, 4.1; 95% CI, 3.4-4.9), antiangiogenic therapy (SHR, 4.4; 95% CI, 3.8-5.2), and immunotherapy (SHR, 3.6; 2.8-4.6). Twelve-month incidence in the cancer cohort increased from 1.0% (95% CI, 0.9% to 1.2%) in 1997 to 3.4% (95% CI, 2.9% to 4.0%) in 2017, which was paralleled by improved 12-month survival and increased use of computed tomography scans, chemotherapy, and targeted therapies. In conclusion, the risk of VTE in cancer patients is increasing steadily and is ninefold higher than in the general population.