The deal, taking effect on September 2, will give family-owned Booths five stores in Cumbria and 26 throughout the north west.
Edwin Booth, chairman on the retail chain, ranked number four in The Grocer Top 50, said: "The business is of a very high quality and we are delighted it is now to become part of the Booths chain."
The Lakes Foodstore was privately owned by a partnership between Keith Graham, Irene Dover and Keith McAdam, and has traded in the town since 1969. Graham said: "The store has enjoyed enormous success but it was felt further development could only be achieved as part of a larger organisation with resources and expertise beyond the reach of an independent operator."
And he said Booths was the "natural" successor for managing the store.