Mathematical modeling projects that worldwide replacement of regular sodium chloride with potassium-enriched salt could prevent 2.96 million deaths annually, representing 14.6% of global cardiovascular and kidney disease mortality. The analysis examined five implementation scenarios, finding that replacing discretionary home-cooking salt would prevent 1.85 million deaths while targeting processed food salt would prevent 1.56 million deaths. Even among people with advanced chronic kidney disease who face hyperkalemia risks, the intervention shows net benefit—preventing 0.75 million deaths while potentially causing 0.10 million deaths from excess potassium. This modeling represents the most comprehensive global assessment of potassium salt substitution to date, building on smaller randomized trials that demonstrated blood pressure benefits. The intervention appears uniquely promising because it requires no behavior change from consumers—simply reformulating existing salt supplies. However, this preprint awaits peer review, and real-world implementation faces regulatory hurdles and cost considerations not captured in the modeling. The projected benefits assume perfect global adoption, which may overestimate practical impact. Still, these findings suggest potassium salt substitution could be among the most effective population-wide interventions for cardiovascular health.