The aim of this study is to investigate whether or not delayed graft function (DGF) and pre-transplant sensitization has a synergistic adverse effect on allograft outcome after deceased donor kidney transplantation (DDKT) using the Korean Organ Transplantation Registry (KOTRY) database, the nationwide prospective cohort. The study included 1,370 cases between May 2014 and June 2019. The cases were divided into 4 subgroups according to pre-sensitization and the development of DGF post-transplant (non-pre-sensitized-DGF(-)(n=1100), non-pre-sensitized-DGF(+)(n=133), pre-sensitized-DGF(-)(n=116), and pre-sensitized-DGF(+)(n=21)). We compared the incidence of biopsy-proven allograft rejection (BPAR), time-related change in allograft function, allograft or patient survival, and post-transplant complications across 4 subgroups. The incidence of overall BPAR and acute antibody-mediated rejection (ABMR) was significantly higher in the pre-sensitized-DGF(+) subgroup than in other 3 subgroups. In addition, multivariable cox regression analysis demonstrated that pre-sensitization combined with DGF is an independent risk factor for both overall BPAR (hazard ratio 3.253, p = 0.005) and acute ABMR (hazard ratio 7.589, p < 0.001). Moreover, DGF and pre-sensitization showed significant interaction. Pre-sensitization combined with DGF did not show significant impact on allograft function, and allograft or patient survival. In conclusion, pre-sensitization and DGF had a synergistic adverse impact on allograft rejection after DDKT.