Guidelines for the diagnosis and treatment of hypertension were published by the American Heart Association (AHA) in 2017. The prevalence of hypertension in adults with congenital heart disease (ACHD) under these guidelines has yet to be characterized. We sought to assess the prevalence, impact, and provider response to hypertension under current guidelines. Data were obtained retrospectively from records of routine clinic visits over a 10 year period. Potential hypertension-related adverse outcomes including stroke, myocardial infarction, surgical intervention for aortic aneurysm, aortic dissection, atrial fibrillation or flutter, cardiac transplantation and death were recorded. The 1070 patients who met inclusion criteria had a mean age of 30.8 ± 10.0 years. The prevalence of hypertension under the 2017 guidelines was 46.6%. Multivariate modeling identified cyanosis, male gender, older age, and overweight/obesity as independent risk factors for hypertension. Guideline-directed management of hypertension in ACHD patients occurred more frequently in ACHD and adult cardiology clinics than in pediatric cardiology clinics (44.1% and 45.1% vs. 24.0%, p < 0.01, respectively). Adverse outcomes were reported in 217 (20%) patients, the most prevalent of which was atrial fibrillation or flutter (11%). Multivariable modelling for any adverse outcome identified older age, hypertension, cyanosis, greater complexity ACHD, and obesity as risk factors. Modifiable risk factors for atherosclerotic cardiovascular disease are common and often under addressed in the ACHD population.