The new stores, mostly in Scotland, have been bought from the Co-operative Group, which was forced to sell off some outlets following its acquisition of Somerfield. They bring the group's current estate to 18.
Chairman Arthur Harris said: "We will have all 18 supermarkets running under the Haldanes name by Easter, and we are still on the acquisition trail for other stores the length and breadth of the UK.
"In particular, stores in Scotland will include an enhanced range of Scottish foods, and much of the Scottish-sourced produce will be sold in our English outlets, too. We believe there is an appetite for such produce of real quality."
Haldanes, which trades under the "Refreshingly local" banner, claims to be the first mid-sized supermarket chain to open for business in the UK for 27 years.
Harris said trading at the first store to open, in Prestopans near Edinburgh, had "exceeded expectations".