Introduction: Several measures of blood pressure (BP) variability have been associated with kidney disease and cardiovascular events. Although BP is routinely measured during hospitalization in daily practice, the prognostic impact of in-hospital BP and its variability are uncertain. Methods: A total of 226 participants who underwent elective percutaneous coronary intervention (PCI) for stable coronary artery disease (CAD) were included. BP was measured by trained nurses during the 4-day hospitalization for PCI. BP variability was assessed by standard deviation (SD) and coefficient variation of systolic BP. Estimated glomerular filtration rate (eGFR) was calculated at baseline and follow-up (≥6 months). The cardiovascular end point was defined as a composite of cardiovascular death, acute coronary syndrome, stroke, heart failure hospitalization, and any coronary revascularization. Results: In-hospital BP was measured 9.5 ± 0.8 times. During a median follow-up period of 1.7 years, mean eGFR change was −1.7 mL/min/1.73 m<sup>2</sup> per year, and 35 (15.5%) participants met the cardiovascular end point. Mean systolic BP and SD were negatively correlated with eGFR change. In the receiver operating characteristic curve analysis, SD of systolic BP predicted the cardiovascular end point (AUC 0.63, best cutoff value 14.2 mm Hg, p = 0.003). Kaplan-Meier analysis demonstrated a significantly higher incidence of the cardiovascular end point in patients with SD of systolic BP ≥14.2 mm Hg compared to their counterpart ( p = 0.003). A multivariable analysis showed SD of systolic BP as an independent predictor for the cardiovascular end point. When assessed with coefficient variation, BP variability was similarly related to eGFR change and clinical outcomes. Conclusion: Greater in-hospital BP variability was associated with renal function decline and cardiovascular events in patients with stable CAD.