Hypertension is highly prevalent in Chile. The National Health Survey 2016-17 reported a 27.6% prevalence, 68.7% awareness, and 33.3% of hypertensives had controlled blood pressure (BP). May Measurement Month (MMM) is a global initiative aimed at raising awareness of high BP and to act as a temporary solution to the lack of screening programmes worldwide. A cross-sectional survey of volunteers aged ≥18 years old was carried out in May 2018. Blood pressure measurement, the definition of hypertension, and statistical analysis followed the MMM protocol. Ninety-four sites participated, most of them from the Public Health System outpatient clinics distributed along the country. In addition, universities, clinical research sites, and private clinics participated. Hypertension was diagnosed as mean systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg or receiving antihypertensive medication. Overall 9344 individuals were screened. After multiple imputation, hypertension prevalence was 29.2%, of which 64.0% were aware of their condition. Of those aware of their hypertension diagnosis, 87.7% were receiving antihypertensive medication and 56.1% of the total number of hypertensives were on antihypertensive medication. Moreover, 15.3% of the participants who were not receiving treatment were considered potential hypertensives identified in the MMM18. MMM18 was one of the largest BP screening campaigns performed in Chile. It demonstrated a high prevalence of hypertension with one-third of these individuals having controlled BP. The high percentage of persons untreated or with uncontrolled hypertension while on pharmacologic treatment suggests that systematic screening programmes may be a useful tool to improve hypertension control in Chile.