To evaluate the cardiovascular mortality risk in association with blood pressure level among people with and without antihypertensive treatment, we performed the participant-level meta-analysis that included 39 705 Japanese from 6 cohorts (58.4% women; mean age, 60.1 years; 20.4% treated). Multivariable-adjusted Cox models were used to analyze the risk of cardiovascular mortality and its subtypes among 6 blood pressure levels according to recent guidelines, optimal to Grade 3 hypertension, and the usage of antihypertensive medication at baseline. During median 10.0 years of follow-up, there were 2032 cardiovascular deaths (5.1 per 1000 person-years), of which 410 deaths were coronary heart disease, 371 were heart failure, and 903 deaths were stroke. Treated participants had significantly higher risk for cardiovascular mortality (hazard ratios, 1.50; 95% confidence intervals, 1.36-1.66), coronary heart disease (hazard ratios, 1.53; confidence intervals, 1.23-1.90), heart failure (hazard ratios, 1.39; confidence intervals, 1.09-1.76), and stroke (hazard ratios, 1.48; confidence intervals, 1.28-1.72) compared with untreated people. Among untreated participants, the risks increased linearly with an increment of blood pressure category (P0.011). The risk increments per blood pressure category were higher in young participants (<60 years; 22% to 79%) than those in old people (60 years; 7% to 15%) with significant interaction for total cardiovascular, heart failure, and stroke mortality (P0.026). Among treated participants, the significant linear association was also observed for cardiovascular mortality (P=0.0003), whereas no stepwise increase in stroke death was observed (P=0.19). The risks of cardiovascular mortality were approximate to 1.5-fold high in participants under antihypertensive medication. More attention should be paid to the residual cardiovascular risks in treated patients.