Background Acute kidney injury (AKI) after transcatheter aortic valve replacement (TAVR) is associated with increased mortality. However, it is controversial whether AKI affects prognosis per se, being linked to baseline chronic kidney disease (CKD) and bleeding complications. The aim of this study was to disentangle, applying mediation analysis, the association between AKI and clinical outcome, considering CKD and bleedings. Methods and Results Consecutive patients undergoing TAVR were prospectively enrolled at 5 high-volume centers in Italy. AKI was defined according to Valve Academic Research Consortium-3 consensus, whereas bleeding with Bleeding Academic Research Consortium. Primary outcome was all-cause mortality after 1-year follow-up. Among 2621 patients undergoing TAVR, AKI occurrence was associated with 1-year mortality. This association of AKI with the primary end points remained significant after adjusting for baseline risk estimators, either Society of Thoracic Surgeons score (hazard ratio [HR], 2.78 [95% CI, 1.95-3.80], <0.001) or EuroSCORE-II (HR, 1.85 [95% CI, 1.35-2.56], <0.001). Both AKI and CKD significantly and independently affected primary outcome (HR, 3.06 [95% CI, 2.01-4.64], <0.001 and HR, 1.82 [95% CI 1.27-2.65], <0.01, respectively). The estimated proportion of the total effect of CKD mediated via AKI was, on average, 15%, 95% CI, 4%-29%, <0.001. The significant effect of Bleeding Academic Research Consortium 2-5 bleedings on the primary outcome was not mediated by AKI. Conclusions AKI occurs in 1 out of 6 patients and significantly mediates one fifth of the effect of baseline CKD on all-cause mortality after TAVR. Our analysis supports a systematic effort to prevent AKI during TAVR, which may potentially translate into improved patients' 1-year survival.