Objective: To investigate the incidence and risk factors of cardiovascular complications amongst patients with colorectal cancer (CRC). Methods: A retrospective cohort study was conducted on 2085 patients diagnosed with CRC in two tertiary hospitals in China between 2015 and 2020. The patients' medical records were reviewed to identify cardiovascular complications, including myocardial infarction, heart failure, stroke, hypertension, coronary heart disease, heart failure, and arrhythmia. The incidence rate of cardiovascular complications was calculated, and Cox proportional hazards regression analysis was used to identify risk factors. Results: Of the 2085 CRC patients, 329 (15.8%) experienced cardiovascular complications during the follow-up period, with an incidence rate of 17.4 cases per 1000 person-years. The risk was significantly higher in patients who were older than 60 years (adjusted hazard ratio [HR] 2.04, 95% confidence interval [CI] 1.22–3.41), had a higher level of low-density lipoprotein cholesterol (LDL-C) (adjusted HR 2.32, 95% CI 1.31–4.10), had higher levels of serum C-reactive protein (CRP) (adjusted HR 1.57, 95% CI 1.21–2.04), or who underwent chemotherapy or radiotherapy. CRC patients with cardiovascular complications had significantly higher levels of oxidative stress markers, including malondialdehyde (MDA) (5.8 ± 1.2 μmol/L vs. 3.4 ± 0.9 μmol/L, p < 0.001), lower levels of superoxide dismutase (SOD) (85.2 ± 15.6 U/mg protein vs. 112.5 ± 21.3 U/mg protein, p < 0.001), and lower levels of glutathione peroxidase (GPx) (15.6 ± 3.2 U/mg protein vs. 20.4 ± 4.1 U/mg protein, p < 0.001) compared to those without complications. A progressive increase was observed in the proportion of CRC patients with cardiovascular complications over time, rising from 10% in the first year to 38% by the tenth year of follow-up. Conclusion: Cardiovascular complications pose a high risk in CRC patients, particularly amongst older patients and those with higher levels of LDL-C or CRP. Regular monitoring of cardiovascular function should be considered in the management of patients with CRC.