Abstract Background Although balancing treatment efficacy with risks of complications is critical for older adults with aggressive non-Hodgkin lymphoma (NHL), few studies have described these patients’ clinical outcomes, rates of toxicities, and health care utilization. Methods We conducted a retrospective analysis of adults ≥65 years diagnosed with aggressive NHL and receiving systemic therapy at Massachusetts General Hospital from April 2000 to July 2020. We abstracted patient characteristics, clinical outcomes, treatment toxicity, unplanned hospitalizations, and intensive care unit (ICU) admissions within 6 months of treatment initiation from the medical record. Using multivariable logistic regression, we examined factors associated with rates of grade 3+ nonhematologic toxicity and unplanned hospitalization. Results Among 295 patients (median age, 73 years; 39.0% female), 5-year overall survival (OS) was 74.2%. Five-year OS by age group (65–69, 70–74, 75–79, and 80+ years) was 82.2%, 72.0%, 73.6%, and 66.4%, respectively. Overall, 42.4% experienced grade 3+ toxicity, with 8.1% experiencing grades 4–5. The rates of unplanned hospitalization and ICU admission were 41.0% and 6.1%, respectively. In multivariable analysis, hypoalbuminemia (odds ratio [OR], 4.29; p < .001) and high comorbidity score (OR, 4.22; p < .001) were associated with likelihood of grade 3+ toxicity. Hypoalbuminemia (OR, 2.83; p = .003), high comorbidity score (OR, 3.93; p = .001), and receipt of EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin; OR, 5.45; p = .012) were associated with likelihood of unplanned hospitalization. Conclusions The majority of older adults receiving upfront therapy for aggressive NHL survive beyond 5 years, yet nearly half experience substantial treatment toxicities and unplanned hospitalizations. Our findings underscore the need for supportive care interventions to enhance the care experience of this population. Implications for Practice The results of this study highlight the potential benefits of intensive chemoimmunotherapy for the majority of older adults with aggressive non-Hodgkin lymphoma, even at advanced ages. Nearly half of older adults experienced substantial treatment toxicities and unplanned hospitalizations, emphasizing the unmet need for supportive care interventions in this population. The present study also identified hypoalbuminemia and patient comorbidity score as factors associated with grade 3+ nonhematologic toxicity and unplanned hospitalization. These findings may guide the development and implementation of targeted supportive care interventions in high-risk older adults with aggressive non-Hodgkin lymphoma.