We aim to investigate cardiovascular mortality risk among diffuse large B-cell lymphoma (DLBCL) patients and explore cardiovascular mortality trends in the past decades in United States. We extracted data from the Surveillance, Epidemiology, and End Results database for adult patients diagnosed with DLBCL between 1975 and 2019. Standardized mortality ratio, joinpoint regression analysis, and competing risk model were analyzed. Overall, 49,918 patients were enrolled, of whom 4167 (8.3%) cardiovascular deaths were observed, which was 1.22 times the number expected (95%CI, 1.19-1.26). During 1985-2019, the incidence-based cardiovascular mortality rate increased by 0.98% per year (95%CI, 0.58-1.39%), with statistically significant increases in age groups younger than 75 years. The cumulative mortality from cardiovascular disease increased by age but never exceeded that from DLBCL. Older age, male sex, earlier year of diagnosis, lower tumor stage at diagnosis, chemotherapy, radiotherapy, and surgery were all poor prognostic factors for cardiovascular mortality.