Background Acute kidney injury is a serious complication following cardiac surgery associated with mortality. Restricted oxygen delivery is a potential risk factor for acute kidney injury. The aim of this study was to investigate the impact of the duration of low oxygen delivery (<272 mL min−1 m−2), during cardiopulmonary bypass on kidney function. Methods Patients undergoing coronary artery bypass graft surgery ± valve repair were included n = 1968. Oxygen delivery was monitored during cardiopulmonary bypass. Data were explored using multiple regression analyses regarding association between low oxygen delivery and renal replacement therapy (RRT), acute kidney injury (AKI) and post‐operative peak serum creatinine (PPSC). Results Post‐operative peak serum creatinine, incidence of acute kidney injury, and need for dialysis increased in a dose‐dependent manner in relation to duration of a mean oxygen delivery <272 mL min−1 m−2. Using multiple regression analyses, only exposure for at least 30 minutes was independently associated with increased PPSC and AKI. In contrast, both short (1‐5 min, OR: 2.58 1.20, 5.54; P = .015) and at least 30‐minute (OR: 2.85 1.27‐6.41; P = .011) exposure to low DO2 were both independently associated with the need for RRT. Conclusion A low oxygen delivery during cardiopulmonary bypass was in a dose‐dependent manner associated with an increased risk of renal injury.