A study of 89,000 post-menopausal women found walking significantly protected the heart, no matter what other forms of exercise they did. And the benefits applied to all women, no matter their weight.
The research, by cardiologists at Brown University in the United States, tracked women over the age of 50 for ten years.
They found women who walked once a week, for any length of time, saw their risk of heart failure drop 5 per cent, but after this the benefits increase further, dropping 20 per cent if they walked twice or more, and by 35 per cent if they walked every day.
And if those walks were longer than 40 minutes the benefits increased by an additional 25 per cent, they found.
Walking speed also made a difference, with fast walkers 38 per cent less likely to suffer heart failure than casual walkers.
Heart failure, which occurs when the heart stops properly pumping blood around the body, is major problem in the UK, affecting 900,000 people.
In severe cases people with heart failure are left unable to walk up a flight of stairs and are often left breathless, even when resting.
A third of patients die within a year of developing the condition - a survival rate worse than many cancers.
Study leader Dr Somwail Rasla said: "We already know that physical activity lowers the risk of heart failure, but there may be a misconception that simply walking isn't enough."
"Our analysis shows walking is not only an accessible form of exercise but almost equal to all different types of exercise that have been studied before in terms of lowering heart failure risk."
"Essentially, we can reach a comparable energetic expenditure through walking that we gain from other types of physical activity."
Because walking can be done any time and requires no special equipment, the researchers said the results put physical activity within reach for older women who can be put off by busy gyms or sports clubs.