Predicting future kidney allograft function is challenging. Novel biomarkers, such as urinary Dickkopf-3 (uDKK3), may help guide donor selection and improve allograft outcomes. In this prospective multicenter pilot trial, we investigated whether donor uDKK3 reflects organ quality and is associated with future allograft function. We measured uDKK3/crea ratios (uDKK3/crea) from 95 deceased and 46 living kidney donors. Prenephrectomy uDKK3/crea levels were 100× higher in deceased than in living donors (9888 pg/mg vs 113 pg/mg; P < .001). Among deceased donor transplantations, recipients were stratified by their corresponding uDKK3/crea donor levels ranging below (group A, n = 68) or above (group B, n = 65) median. The primary end point of best estimated glomerular filtration rate (eGFR) within the first 3 months after kidney transplantation was superior in group A (56.3 mL/min/1.73 m2) than that in group B (44.2 mL/min/1.73 m2; P = .0139). Second, the composite clinical end point consisting of death, allograft failure or eGFR decline >50% occurred less frequent in group A. By mixed linear regression modeling, donor uDKK3/crea remained an independent predictor of eGFR after transplantation, with a slope of -4.282 mL/min/1.73 m2 per logarithmic increase in donor uDKK3/crea. In summary, uDKK3 may serve as a noninvasive, donor-dependent biomarker for assessing organ quality and future allograft function.