Patients with relapsed diffuse large B-cell lymphoma (DLBCL) who have failed or are ineligible for autologous haematopoietic cell transplantation (HCT) have a poor prognosis. We examined the outcomes of non-myeloablative allogeneic HCT in this setting. Thirty-one patients with DLBCL and one patient with Burkitt lymphoma received allogeneic HCT following 2 Gy total body irradiation with or without fludarabine. Median age was 52 years. Twenty-four patients (75%) had undergone prior autologous HCT. Disease status at HCT was complete response (14/32, 44%), partial response (9/32, 28%), or refractory (9/32, 28%). Cumulative incidences of acute graft-versus-host disease (GVHD) grades II–IV, grades III–IV, and chronic GVHD were 53%, 19%, and 47% respectively. With a median follow-up of 45 months, 3-year estimated overall (OS) and progression-free survival (PFS) was 45% and 35% respectively. Three-year cumulative incidences of relapse and non-relapse mortality were 41% and 25% respectively. In multivariate models, chemosensitive disease and receipt of ≥4 lines of treatment before HCT were associated with better OS. Patients with chemosensitive disease had 3-year OS and PFS of 56% and 43% respectively. Non-myeloablative allogeneic HCT can produce long-term disease-free survival in patients with chemosensitive relapsed DLBCL who have failed or are ineligible for autologous HCT.