Improving hypertension control in sub-Saharan Africa is an important global health priority yet there is no direct evidence on the expected mortality benefits of reducing blood pressure (BP) to different targets. We use nationally representative longitudinal data from five waves of the South African National Income Dynamics Study to estimate the relationship between systolic BP (SBP) and six-year all-cause mortality and compare the number of deaths averted from scaling up SBP care under different thresholds. We found that the association between SBP and mortality is weaker in South Africa than in high-income and many low- and middle-income countries. As such, at the population level, we find that scaling up care under a more conservative 150 mmHg threshold results in the most efficient mortality benefits in terms of deaths averted (3.3 deaths averted per 1,000 population) relative to the share of the total population that would require care (16%).