The Co-op is rebranding Somerfield stores across the country
The Co-operative Group has posted a 17% rise in first-half profit, boosted by its food business.
The funeral-to-banking group, which bought supermarket chain Somerfield in 2008, made a pre-tax profit of £228.8m.
The Co-op, Britain's fifth-biggest chain of grocery stores, reported that sales in its shops rose 7.3% in the 28 weeks to 25 July.
Sales of its Simply Value range soared by 80%, while purchases of Fairtrade products grew by 35%.
Earnings at Co-operative Financial Services increased by 11%.
Speaking on BBC Radio 5 live, Chief Executive Peter Marks said the figures proved the company was taking customers away from its competitors.
"When I said we were acquiring Somerfield, I also said that we'd use some of the savings to reduce our prices which we've done," he said.
"We've improved our product range, spent a lot of money modernising our stores and all of that together has meant that we're getting new customers."
The company, which was created in 2006 from the merger of the Co-operative Group and United Co-operatives, also runs Britain's third-biggest pharmacy chain and its largest independent travel business. It is also the number one provider of funeral services.
The group, which has about 4.5 million members and 5,300 retail outlets, traces its roots back to the founding of the co-operative movement in Rochdale, north-west England, in 1844.