Kidney delayed graft function (DGF) remains common after simultaneous liver–kidney (SLK) transplantation, yet its long-term implications for graft and recipient survival are incompletely defined.

Using the Scientific Registry of Transplant Recipients, we analyzed adult SLK recipients (2014–2025), stratified by kidney DGF, defined as receiving dialysis within the first postoperative week. To isolate the association between DGF and long-term outcomes and limit confounding due to primary non-function, recipient and graft survival analyses were conducted using a 90-day landmark analysis. Multivariable logistic regression identified predictors of DGF. Cox proportional hazards models evaluated death-censored kidney graft survival and overall recipient survival.

Among 3268 SLK recipients, 890 (27.2%) developed kidney DGF. Independent predictors of DGF included pre-transplant dialysis (OR 2.79, 95% CI 2.31–3.38; p < 0.001), higher model for end stage liver disease (MELD) score (OR 1.03 per point, 95% CI 1.01–1.04; p < 0.001), metabolic-dysfunction-associated-steatohepatitis (MASH) etiology (OR 1.45, 95% CI 1.10–1.93; p = 0.009), cold ischemia time (OR 1.02 per hour, 95% CI 1.01–1.04; p < 0.001), post acuity circle era (OR 1.28, 95% CI 1.04–1.58; p = 0.018), and higher KDRI (OR 1.12 per 0.1 increase, 95% CI 1.06–1.18; p < 0.001). In the primary cohort, DGF was not independently associated with death-censored kidney graft failure (HR 1.30, 95% CI 0.80–2.11; p = 0.29) but was associated with inferior recipient survival (HR 1.33, 95% CI 1.09–1.63; p = 0.005). Sensitivity analyses in the unrestricted cohort confirmed the mortality association, while DGF was also associated with death-censored kidney graft failure (DCGF).

Kidney DGF after SLK transplantation is associated with recipient and donor risk factors and inferior long-term recipient survival, while its association with long-term kidney graft outcomes warrants further investigation.