We reported findings from participants screened during the May Measurement Month 2021 in China, which aimed to raise awareness of raised blood pressure (BP), and to investigate the risk factors of BP. The study participants were adults (≥18 years), ideally in whom BP had not been measured in the previous year. Blood pressure was measured three times consecutively with 1 min intervals in the sitting position, using a validated upper-arm cuff automated BP monitor (Omron HEM-7081IT), and transmitted to a central cloud database via a smartphone app. The measurement was performed in 218 844 participants in 183 sites across 31 China provinces. The mean (standard deviation) age was 47.0 (15.7) years, and 51.8% (n = 113 466) were women. The mean systolic/diastolic BP was 120.2/77.5 mmHg. Among 57 178 (26.1%) participants with hypertension, the awareness, treatment, and control rates of hypertension were 30.4% (n = 17 354), 28.7% (n = 16 369), and 17.1% (n = 9743), respectively. After adjustment for age, sex, and use of antihypertensive medication, both systolic and diastolic BP were significantly (P ≤ 0.01) higher in current smokers (n = 22 344, +0.4/+0.7 mmHg) and with moderate (n = 4780, +1.4/+4.2 mmHg) or daily alcohol intake (n = 2427, +1.3/+2.5 mmHg). Blood pressure was lower in those reporting regular exercise (n = 32 328, -2.2/-1.4 mmHg). In addition, individuals with previous COVID-19 vaccination had lower systolic and diastolic BP (n = 88 945, -1.8/-1.5 mmHg, P ≤ 0.001). In conclusion, our study showed that long-term large-scale screening for hypertension is feasible, and there is a strong association between BP and major lifestyle factors.