To determine the proportion with hypertension among opportunistic screenees in the Republic of the Congo. This cross-sectional study was conducted in Republic of the Congo in May 2018. This screening was done in urban and rural areas that included Brazzaville, Pointe-Noire, District of Ngoyo, and District of Nkayi. The study protocol was provided by the International Society of Hypertension, and local ethical clearance was obtained. The data were processed by the May Measurement Month global project team. In total, 6169 people were screened, 2418 of which were female (39.2%). Most of the people screened were from 18 to 29 years old (n = 4184, 67.8%). The proportion of hypertension found was 22.2% (n = 1371). Among the hypertensive patients, 40.2% were aware of their hypertension, but only 493 (36.0%) were on antihypertensive treatment, and only 16.0% were controlled. The frequency of diabetes was 2.2% (n = 135), 2.3% (n = 139) had a previous stroke, and overweight and obesity were present in 15.4% (n = 952) and 7.3% (n = 449), respectively. Hypertension is frequent in the Republic of the Congo, and levels of awareness, treatment and control are low. Actions are needed to increase access of all to a correct diagnosis and treatment of hypertension to achieve universal health coverage.