Tesco has said it is reviewing its promotions and labels after an audit showed that two thirds of produce grown for bagged salad is wasted.
The research also shows that almost half of all bakery products and 40 percent of all apples sold in Tesco stores go to waste.
But this is just the tip of a food waste ice burg in the UK and Tesco is currently the only major retailer to measure and report food waste for its entire supply chain, from field to fork.
The move has been welcomed by food campaigners, but many also say the supermarkets have much further to go in reducing levels of waste.
ITV News correspondent Richard Pallot reports:
Some 15 million tonnes of food is wasted in the UK every year, according to estimates by the Waste and Resources Action Programme (Wrap).
The majority occurs at farm level, but campaigners say that supermarkets have a role to play well beyond their premises.
Domnika Jarosz, of campaign group Feeding the 5000, said supermarkets "control a large part of the supply chain".
"Their strict cosmetic standards - which reject straight bananas and cracked cauliflowers, for example - mean there is a significant amount of waste before products even reach the shelf," she told ITV News.
The findings also show that a significant proportion of wastage occurs in households. One in three bagged salads is thrown away at home, and one in four apples.
The average family spends £700 per year on food that is never eaten, the research shows.
Tesco says it is changing its practices in light of the findings, by ending 'Buy One, Get One Free' offers on large bags of salad and developing mix-and-match promotions for smaller bags.
It is also removing 'display until' dates from fresh fruit and vegetables, using smaller cases in stores and rearranging 600 in-store bakeries to improve stock control.
It said it was involved in trials with farmers and will provide more tips for customers on reducing waste at home.
Wrap director Richard Swannell said: "We welcome Tesco's approach to tackling food waste across their whole supply chain, and by identifying the hot spots they can tackle these areas effectively.
"Food waste is a global issue and collaborative action is essential if we are to successfully reduce food waste and reap the financial and environmental benefits of doing so."