BackgroundStudies have reported age as a risk factor for cardiovascular disease (CVD)‐related mortality; however, only a few studies have focused on the relationship between age and CVD‐related mortality, especially among major gastrointestinal cancers.MethodThe present retrospective cohort enrolled patients with colorectal, pancreatic, hepatocellular, gastric, and esophageal cancer between 2000 to 2015 from the Surveillance, Epidemiology and End Results Registry (SEER). Standardized mortality ratio (SMR), competing risk regression, and restricted cubic spline (RCS) analyses were used in our study.ResultsWe analyzed 576,713 patients with major gastrointestinal cancers (327,800 patients with colorectal cancer, 93,310 with pancreatic cancer, 69,757 with hepatocellular cancer, 52,024 with gastric cancer, and 33,822 with esophageal cancer). Overall, CVD‐related mortality gradually decreased every year, and the majority were older patients. All cancer patients had a higher CVD‐related mortality rate than the general U.S. population. The adjusted sub‐hazard ratios for middle‐aged with colorectal cancer, pancreatic cancer, hepatocellular cancer, gastric cancer, and esophageal cancer were 2.55 (95% CI: 2.15–3.03), 1.77 (95% CI: 1.06–2.97), 2.64 (95% CI: 1.60–4.36), 2.15 (95% CI: 1.32–3.51), and 2.28 (95% CI: 1.17–4.44), respectively. The adjusted sub‐hazard ratios for older patients with colorectal cancer, pancreatic cancer, hepatocellular cancer, gastric cancer, and esophageal cancer were 11.23 (95% CI: 9.50–13.27), 4.05 (95% CI: 2.46–6.66), 4.47 (95% CI: 2.72–7.35), 7.16 (95% CI: 4.49–11.41), and 4.40 (95% CI: 2.28–8.48), respectively. A non‐linear relationship between age at diagnosis and CVD‐related mortality was found in colorectal cancer, pancreatic cancer, and esophageal cancer; their reference ages were 67, 69, and 66 years old, respectively.ConclusionThis study demonstrated that age was a risk factor for CVD‐related mortality among major gastrointestinal cancers.