Anti-poverty campaigner Jack Monroe says she was feeling overwhelmed and "cried quietly" to herself after supermarkets pledged to stock their value ranges in more stores.
Ms Monroe's tweets highlighted the rapid increase in prices of some products at supermarkets, all contributing to the rise in food costs.
In response to her campaign, Asda said it would stock its Smart Price and Farm Stores ranges in all 581 food stores and online by March 1 to help its customers with the cost-of-living crisis.
“I am just glad it makes things a little bit easier for people," Ms Monroe told GMB.
"It is a lovely, feel good news story... the difference it makes to people being able to buy food."
Ms Monroe previously discussed how she was having to put food back on the shelves as her budget no longer stretched as far as it previously did.
All Asda branches will have the full range of 200 Smart Price and Farm Stores lines, the company said.
It confirmed on Saturday that the full range is already available online.
Monroe shared photos of products at Asda in Shoeburyness, Essex, that have reverted to their price from a year ago.
In one tweet, she said she found a kilogram bag of rice that was back to its old price of 45p, after jumping last month to £1 for 500g – a price increase of 344%.She wrote: “I was very quick to vilify Asda for what I saw as a change of direction for their company, and a watering down of their commitment to an entire group of their customers.”
The company promised to “do better”, she said, as she praised the “remarkable” speed of the turnaround.
“The impact that this will have on millions of people, is impossible to overstate,” she said, adding that she “cried, quietly, to myself, in Asda” at the development.
She also wrote: “So I guess I just wanted to say thanks to everyone at Asda who has worked really hard over the last few weeks to bring the missing SmartPrice products back.”