Survival rates of patients with non-Hodgkin lymphoma (NHL) have improved over the last decade. However, cardiotoxicities remain important adverse consequences of treatment with chemotherapy and radiation, although the burden of cardiovascular mortality (CVM) in such patients remains unknown. We conducted a retrospective cohort study of patients greater than or equal to 20 years of age diagnosed with diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) between 2000 and 2013 using data extracted from the United States Surveillance, Epidemiology, and End Results (SEER) database. Our primary endpoint was CVM. The association between NHL and CVM was evaluated using multivariable Cox regression analysis after adjusting for other patient characteristics. We calculated standardized mortality ratios (SMRs) for CVM, comparing NHL patients with the general population. We identified 153 983 patients who met the inclusion criteria (69 329 with DLBCL, 48 650 with CLL/SLL, and 36 004 with FL). The median follow-up was 37 months (interquartile range, 10-78 months); the mean patient age was 66.24 (±14.69) years; 84 924 (55.2%) were men; 134 720 (87.5%) were White, and 131 912 (85.7%) did not receive radiation therapy. Overall, 9017 patients (5.8%) died from cardiovascular disease, and we found that NHL patients had a higher risk of CVM than the general population, after adjusting for age (SMR 15.2, 95% confidence interval: 14.89-15.52). The rates of CVM were 5.1%, 8%, and 4.4% in patients with DLBCL, CLL/SLL, and FL, respectively. Furthermore, across all NHL subtypes, older age, higher stage at the time of diagnosis (particularly stage 4), male sex, and living in the south were associated with higher risks of CVM. Our data suggest that risk assessment and careful cardiac monitoring are recommended for NHL patients, particularly those with the CLL/SLL subtypes.