The use of chimeric antigen receptor (CAR) T-cell therapy after a second relapse of diffuse large B-cell lymphoma (DLBCL) has shown favorable efficacy in clinical trials; however, little is known about health care resource utilization (HCRU) and costs of CAR T cell therapy for patients treated in real-world settings. We assessed treatment patterns, HCRU, costs, and safety in patients receiving CAR T cell therapy for relapsed or refractory DLBCL across 3 US commercial claims databases. Adults with DLBCL treated with CAR T cell therapy were identified in the following 3 claims databases: Optum® Clinformatics® Data Mart, IBM MarketScan® Commercial & Medicare Database, and IQVIA PharMetrics® Plus. Mean total costs were calculated and adjusted to 2019 US dollars. HCRU and costs within 3 months of infusion were stratified by safety events of interest, including neurological events (NEs) and cytokine release syndrome (CRS), identified via unvalidated algorithms designed based on expert medical opinion. A total of 191 patients receiving CAR T cell therapy were identified across the databases; their median age ranged from 56 to 67 years, and 63% to 75% were male. Most patients (88% to 98%) received CAR T cell infusions in the inpatient setting; 30% to 75% received bridging therapy. CRS was reported in 75% to 84% of patients (severe CRS, 15% to 32%), and NEs were reported in 58% to 69% (severe NEs, 25% to 43%). Mean total inpatient hospital days ranged from 17 to 22 days and increased with severe CRS (19 to 27 days) or severe NEs (22 to 29 days). Mean total health care expenditures ranged from $380,000 to $526,000 and were generally higher with severe CRS or NEs (∼$406,000 to $679,000). HCRU and costs associated with CAR T cell therapy may vary in the real world depending on several factors, including occurrence and severity of adverse events.