Background <p>Intraoperative hypotension is associated with a postoperative decline in renal function, and the effect of personalized blood pressure control on renal function remains unknown. The aim of this study was to investigate the effects of individualized intraoperative blood pressure management on renal function and serum microRNA-21-5p levels in older patients with hypertension after major gastrointestinal surgery.</p> Methods <p>A total of 220 patients scheduled for elective major gastrointestinal surgery were randomly divided into two groups: conventional blood pressure management (Group C) and individualized blood pressure management (Group S), with 110 patients in each group. In Group S, blood pressure was controlled within ± 10% of baseline systolic blood pressure or ± 20% of baseline mean arterial pressure. Moderately open fluid management strategies were adopted in both groups. Blood samples were collected from all patients before and after surgery to measure creatinine and microRNA-21-5p levels.</p> Results <p>The creatinine level was significantly lower in Group S than in Group C 7 days after surgery (<i>P</i> &lt; 0.05), and the reduction in creatinine levels in the week following surgery was also significantly greater in Group S than in Group C (<i>P</i> &lt; 0.05).</p> Conclusion <p>Intraoperative individualized blood pressure management could reduce the release of microRNA-21-5p related to renal injury and attenuate the increase in postoperative creatinine levels in older patients with hypertension.</p>