The multicenter, prospective phase 2 Australasian Leukaemia & Lymphoma Group NHL29 trial was conducted to assess the addition of ibrutinib to R-mini-CHOP (dose attenuated R-CHOP; rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) in patients aged ≥75 years with newly diagnosed diffuse large B-cell lymphoma (DLBCL). Treatment consisted of six 21-day cycles of ibrutinib–R-mini-CHOP followed by two 21-day cycles of R-ibrutinib. Coprimary end points were deliverability and 2-year overall survival (OS). The median average relative total dose and average relative dose intensity for the entire regimen were both 97% (interquartile range, 82-100 and 88-100, respectively). With a median follow-up of 35.5 months, the 2-year OS was 68% (95% confidence interval [CI], 55.6-77.4) with a 2-year progression-free survival (PFS) of 60.0% (95% CI, 47.7-70.3). Median OS and PFS were 72 months (95% CI, 35 to not reached) and 40 months (95% CI, 20.4 to not reached), respectively. The overall response rate was 76% (61/79) of patients, with a complete response rate of 71% (56/79). Deaths occurred in 34 of 79 patients (43%), including 17 from progressive disease and 5 treatment related. Overall, 67% patients experienced at least 1 serious adverse event. Most common adverse events were infections and diarrhea (the majority grade 1-2). In both health-related quality of life measures, there was an improvement in functional and symptom scales, median health state classification score, and median visual analogue scale in responders over time. In conclusion, this study showed that the addition of ibrutinib to R-mini-CHOP was both deliverable and efficacious in elderly DLBCL patients.