Summary For diffuse large B‐cell lymphoma ( DLBCL ) patients progressing after autologous haematopoietic cell transplantation (auto HCT ), allogeneic HCT (allo HCT ) is often considered, although limited information is available to guide patient selection. Using the Center for International Blood and Marrow Transplant Research ( CIBMTR ) database, we identified 503 patients who underwent allo HCT after disease progression/relapse following a prior auto HCT . The 3‐year probabilities of non‐relapse mortality, progression/relapse, progression‐free survival ( PFS ) and overall survival ( OS ) were 30, 38, 31 and 37% respectively. Factors associated with inferior PFS on multivariate analysis included Karnofsky performance status ( KPS ) <80, chemoresistance, auto HCT to allo HCT interval <1‐year and myeloablative conditioning. Factors associated with worse OS on multivariate analysis included KPS <80, chemoresistance and myeloablative conditioning. Three adverse prognostic factors were used to construct a prognostic model for PFS , including KPS <80 (4 points), auto HCT to allo HCT interval <1‐year (2 points) and chemoresistant disease at allo HCT (5 points). This CIBMTR prognostic model classified patients into four groups: low‐risk (0 points), intermediate‐risk (2‐5 points), high‐risk (6‐9 points) or very high‐risk (11 points), predicting 3‐year PFS of 40, 32, 11 and 6%, respectively, with 3‐year OS probabilities of 43, 39, 19 and 11% respectively. In conclusion, the CIBMTR prognostic model identifies a subgroup of DLBCL patients experiencing long‐term survival with allo HCT after a failed prior auto HCT .