Background: Antihypertensive medicines are effective in reducing adverse cardiovascular events. Our aim was to compare hypertension awareness, treatment and control, and how they have changed over time, in high-income countries. Methods: We used data on 526,336 participants aged 40-79 years in 123 national health examination surveys from 1976 to 2017 in twelve high-income countries: Australia, Canada, Finland, Germany, Ireland, Italy, Japan, New Zealand, South Korea, Spain, the UK, and the USA. We calculated the percent of participants with hypertension – defined as systolic blood pressure ≥140mmHg or diastolic blood pressure ≥90mmHg or being on pharmacological treatment for hypertension – who were aware of their condition, who were treated, and whose hypertension was controlled (i.e. lower than 140/90 mmHg). Findings: Canada, South Korea, Australia and the UK have the lowest prevalence of hypertension, and Finland the highest. In the 1980s and early 1990s, treatment rates were at most 40% and control rates were below 25% in most countries and age-sex groups. Over time, hypertension awareness and treatment increased and control rate improved in all twelve countries, with South Korea and Germany experiencing the largest improvements. Most of the increase occurred in the 1990s and early-mid 2000s, having plateaued since in most countries.Canada, Germany, South Korea and the USA have the highest rates of awareness, treatment and control, while Finland, Ireland, Japan and Spain the lowest. Even in the best performing countries, treatment coverage was at most 80% and control rates were below 70%. Interpretation: Hypertension awareness, treatment and control have improved substantially in high-income countries since the 1980s and 1990s. However, control rates have plateaued in the past decade, at levels lower than those in high-quality hypertension programmes. There is substantial variation across countries in the rates of hypertension diagnosis, treatment and control.