Background: Pretransplant blood transfusion is well-known cause of allosensitization. However, the effects of blood transfusion after kidney transplantation on graft outcomes remain controversial. Methods: We analyzed 785 patients who underwent human leukocyte antigen- and ABO-compatible kidney transplantation between 2014 and 2020. Patients were grouped based on receiving red blood cell transfusion within the first 30 days after transplantation. Results: Overall, 18.9% of patients received red blood cell transfusion within 1 month after transplantation. The median number of packed red cells among transfused recipients was 2 (interquartile range, 1.0–3.0) and the median time to first transfusion was 5.0 days (interquartile range, 2.0–12.0 days). Transfusion group patients were more often women, more often received a deceased donor transplant, and had a longer dialysis vintage compared to no transfusion group patients. During a median follow-up of 53 months, 30 patients (3.8%) died and 39 patients (5.0%) experienced death-censored graft loss. Multivariable analysis confirmed that blood transfusion was independently associated with higher all-cause mortality (hazard ratio, 3.030; 95% confidence interval [CI], 1.438–6.384; P=0.004). Transfusion was also significantly associated with an increased risk of death-censored graft loss (hazard ratio, 2.178; 95% CI, 1.059–4.477; P=0.034). Cumulative probabilities for antibody-mediated rejection was significantly higher in the transfusion group than in the no transfusion group (P=0.012), whereas cumulative probabilities for T cell-mediated rejection between two groups were not significantly different (P=0.694). Conclusions: Transfusion within 1 month after kidney transplantation is associated with increased risk of all-cause mortality, death-censored graft loss, and antibody-mediated rejection.