Elevated blood pressure (BP) is a growing burden worldwide, leading to over 10 million deaths each year. May Measurement Month (MMM) is a global initiative to raise awareness of high BP and acts as a temporary solution to the worldwide shortage of screening programmes. We aimed to screen for hypertension and cardiovascular risk factors in people aged ≥18 years in the community, thereby defining the proportion of participants with elevated BP and assessing the awareness and the effectiveness of its treatment. An opportunistic cross-sectional survey of volunteers aged ≥18 years was carried out in May 2021. Blood pressure measurement, the definition of hypertension, and statistical analysis followed the standard MMM protocol. From May 2021 to June 2021, through three cities/provinces in Vietnam (due to the COVID-19 pandemic), 2572 individuals with mean age 51.5 (SD ±15.7) years were screened. After multiple imputation, 929 (36.1%) had hypertension. Of individuals not receiving antihypertensive medication, 206 (11.2%) were hypertensive. Of individuals receiving antihypertensive medication, 415 (57.4%) had uncontrolled BP (≥140/90 mmHg). The MMM21 BP screening campaign was undertaken in Vietnam during the COVID-19 pandemic. Undiagnosed and uncontrolled hypertension in Vietnam remains a substantial health problem. Local campaigns applying standardized methods such as MMM21 will be beneficial to screen for a significant number of individuals with raised BP and increase awareness of hypertension.