It said those who came on foot visited shops far more frequently than people who drove to make their purchases.
The group pointed to research in its updated report, The Pedestrian Pound, launched in the Grassmarket in Edinburgh today.
It said: "A review of academic evidence in the report shows shoppers on foot can spend up to six times more than those who arrive by car, and that people value walkable destinations and investment in the public realm."
Policy and research co-ordinator Dr Rachel Lee said: "Pedestrians visit more often, as do bus users.
"The fact they visit more often and spend each visit means their total spend adds up to more than people arriving by car over the same period."
She said a London study found those in cars generally visited once a month or less, while half of pedestrians visited daily and one third several times a week.
Living Streets Scotland said the number of people using streets where improvements had been made had increased by up to 35 per cent, in contrast to a 22 per cent decline in footfall overall over the decade to last year.
It said Edinburgh and Kelso were among places with thriving streets.
A spokeswoman said: "When streets are regenerated to boost walking, there is a corresponding impact on turnover, property values and rental yields.
"For well-designed projects, sales can increase by 30 per cent or more when footfall is boosted."
Living Streets Scotland director Stuart Hay said: “Walking has long been undervalued as a minor mode of transport, but is in fact the lifeblood of the high street.
"There is a significant body of academic evidence and examples showing environmental improvements can boost footfall and local economies.
“For too long, the debate has focused solely on parking, instead of getting people out of their cars to support local businesses.
"For town centres to succeed, we need high streets which are safe and attractive for walking, with 20mph zones and cleaner air.
"With less traffic, people will be encouraged to visit and enjoy their local high street more often.”
Transport secretary Michael Matheson said: “This is an important report which underlines the value of walking and footfall to our towns and cities.
“We know that walking benefits individual health and our shared environment, but the benefits do not stop there.
"While the nature of shopping has undoubtedly changed in the last decade, it’s clear footfall on our streets remains an important driving force in our economy."