Analysis of more than 70,000 people in the US and two groups amounting to more than 130,000 in China found that "nut intake was inversely associated with risk of total mortality in all three cohorts".
In the US group there was a reduced risk of total mortality of 21% for individuals who ate the most peanuts, while for the two Chinese studies combined, the figure was 17%.
The study said the findings were observed among men and women and across racial and ethnic groups, and was independent of metabolic conditions, smoking, alcohol consumption and body mass index.
But no significant correlation was found between nut consumption and risk of death due to cancer or diabetes.
The study was published online by JAMA Internal Medicine with an accompanying editorial piece by Mitchell H Katz, director of the Los Angeles County Department of Health Services.
"Peanuts are cheap and ubiquitous (and can be ground into delicious peanut butter!)," he wrote.
"Of course, peanuts are not really nuts (they are legumes since they grow in bushes, unlike tree nuts), but who cares if they help us to live longer at an affordable price."
Professor Peter Weissberg, medical director at the British Heart Foundation, said the public should be clear the study had not found that the more nuts you eat, the lower the risk of heart problems.
"This large study found that death rates from heart attacks were lower in people who eat nuts, particularly peanuts, than in those who don't," he said.
"The results suggest that including a modest amount of nuts as part of a well-balanced diet may be of benefit."
Nuts 'reduce heart disease risk'