The Group will invest almost £2.5m in rebranding and refurbishing the stores.
Owned by Sainsbury's, the stores trade under the names Bells or Jacksons, and are located in York, Middlesbrough, Ossett, Billingham, Thornaby, Wakefield, Nottingham and Leicester, as well as Newton Hall and Chilton in County Durham. The Leicester store is currently closed.
The Co-operative expects to complete on the acquisition within the next six weeks and the stores will be converted to its convenience format, with its emphasis on fresh foods, by the autumn.
Co-operative Group chief executive Peter Marks said: "This is a significant investment in the region for The Co-operative and continues our ambitious programme of growth to sustain market leadership in the convenience sector.
"The stores have great potential and with the benefits we will bring, including our member Share of Profits scheme, we would expect to add significant value to the businesses."