Background The degree of hospital‐level variation in the ratio of percutaneous coronary interventions to coronary artery bypass grafting procedures (PCI:CABG) and the association of the PCI:CABG ratio with clinical outcome are unknown. Methods and Results In a multicenter population‐based study conducted in Ontario, Canada, we identified 44 288 patients from 19 institutions who had nonemergent diagnostic angiograms indicating severe multivessel coronary artery disease (2013–2017) and underwent a coronary revascularization procedure within 90 days. Hospitals were divided into tertiles according to their adjusted PCI:CABG ratio into low (0.70–0.85, n=17 487), medium (1.01–1.17, n=15 275), and high (1.18–1.29, n=11 526) ratio institutions. Compared with low PCI:CABG ratio hospitals, hazard ratios (HRs) for major adverse cardiac and cerebrovascular events were higher at medium (HR, 1.19; 95% CI, 1.14–1.25) and high ratio (HR, 1.21; 95% CI, 1.15–1.27) hospitals during a median 3.3 (interquartile range 2.1–4.6) years follow‐up. When interventional cardiologists performed the diagnostic angiogram, the odds of the patient receiving PCI was higher (odds ratio, 1.37; 95% CI, 1.23–1.52) than when it was performed by noninterventional cardiologists, after accounting for patient characteristics. Having the diagnostic angiogram at an institution without cardiac surgical capabilities was independently associated with a higher risk of major adverse cardiac and cerebrovascular events (HR, 1.07; 95% CI, 1.02–1.11), death (HR, 1.09; 95% CI, 1.02–1.18), and myocardial infarction (HR, 1.10; 95% CI, 1.03–1.17). Conclusions Patients undergoing diagnostic angiography in hospitals with higher PCI:CABG ratio had higher rates of adverse outcomes, including major adverse cardiac and cerebrovascular events, myocardial infarction, and repeat revascularization. Presence of on‐site cardiac surgery was associated with better survival and lower major adverse cardiac and cerebrovascular events.