SummaryThe success of CD19 Chimeric antigen receptor (CAR) T‐cell therapy in large B‐cell lymphoma (LBCL) has been partially offset by toxicity and logistical challenges, which off‐the‐shelf agents like CD20xCD3 bispecific antibodies might potentially overcome. However, when using CAR T outcomes as the ʽstandard‐of‐care comparator̕ for relapsed/refractory (r/r) LBCL, a potential learning curve with implementing a novel, complex therapy like CAR T needs to be considered. To address this, we analysed 726 UK patients intended to be treated with CD19 CAR T for r/r LBCL and compared outcomes between the first year of the national CAR T programme (Era 1; 2019) and the more recent treatment era (Era 2; 2020–2022). We identified significant improvements for Era 2 versus Era 1 in dropout rate (17% vs. 27%, p = 0.001), progression‐free survival (1‐year PFS 50% vs. 32%, p < 0.001) and overall survival (1‐year OS 60% vs. 40%, p < 0.001). We also observed increased use of bridging therapy, improvement in bridging outcomes, more tocilizumab/corticosteroid use, reduced high‐grade cytokine release syndrome (4% vs. 9%, p = 0.01) and intensive care unit admissions (20% vs. 32%, p = 0.001). Our results demonstrate significant improvement in CAR T outcomes over time, highlighting the importance of using up‐to‐date clinical data when comparing CAR T against new treatment options for r/r LBCL.