Double expressor lymphoma (DEL) refers to diffuse large B-cell lymphoma (DLBCL) cases characterized by the overexpression of both MYC and BCL2 proteins, as determined by immunohistochemistry (IHC), without requiring underlying genetic rearrangements. DEL is associated with more aggressive disease behavior and poorer prognosis. This study aimed to assess the impact of DEL on progression-free survival (PFS) and overall survival (OS) compared to non-DEL patients. We conducted a retrospective study at the Hospital, analyzing 177 patients diagnosed with DLBCL between March 2014 and March 2021. Patients were classified as DEL or non-DEL based on immunohistochemical analysis. Survival rates, clinical characteristics, and treatment responses were compared using Kaplan-Meier survival analysis, and multivariable Cox regression was performed to identify independent prognostic factors. Among 177 patients, 113 (63.8%) were DEL and 64 (36.2%) non-DEL. DEL patients had significantly worse outcomes, with a median follow-up of 39.4 months. The 3-year PFS (44.2% vs. 68.8%) and OS (54.9% vs. 81.3%) were significantly lower in DEL (PFS: p < 0.001; OS: p = 0.001). Median PFS in DEL was 19 months. Multivariable analysis confirmed DEL as an independent predictor of worse PFS (HR: 1.488, 95% CI: 1.091-2.03, p = 0.012) and OS (HR: 1.376, 95% CI: 1.011-1.873, p = 0.043). DEL status is strongly linked to poor survival in DLBCL, highlighting the need for targeted therapies beyond R-CHOP. Future research should explore personalized treatment strategies to improve outcomes in this high-risk group.