Combinatorial antiretroviral therapy provided improvement of HIV patients' immune function and a decrease in the incidence of non-Hodgkin lymphoma (NHL). Diffuse large B-cell lymphoma (DLBCL) is one of the most common NHL forms affecting HIV+ patients. The present study aimed to evaluate the impact of HIV infection on the prognosis of patients treated for DLBCL in a reference cancer treatment center in Brazil. A retrospective case-control study was developed with patients followed-up at the Brazilian National Cancer Institute, in which 243 DLBCL patients (91 HIV+ and 152 HIV-) were enrolled. HIV- controls were matched to HIV+ according to date of cancer diagnosis, clinical staging, primary cancer treatment and date of birth. Sociodemographic and cancer treatment data were extracted from medical charts. Kaplan-Meier analyses were carried out to estimate survival, while univariate and multiple Cox regression analyses were used to determine factors associated with mortality. A total of 98 deaths were observed in a 5-year period after cancer diagnosis. A negative association of HIV infection with both overall and disease-specific survival 1 year after cancer diagnosis was observed hazard ratio (HR) = 1.98 and 1.96, respectively. The negative association with HIV infection with disease-specific survival remained significant for a 5-year period after cancer diagnosis (HR = 1.53). HIV viral load above 1000 copies/ml at study entry was also associated with shorter overall and cancer-specific survival. HIV infection negatively impacted prognosis and mortality of DLBCL patients irrespective of cancer-related clinical factors.