Robert Wiseman Dairies has stepped up its campaign to expand into the southwest of England by buying Definitely Devon.
The West Country dairy supplies about 20m litres of milk a year from their Torrington depot, as well as clotted cream.
It was jointly owned by local co-op Torridge Vale and the Co-operative Group.
The price tag of £800,000 is subject to an assessment of the actual volume of milk being transferred.
Wiseman will continue to supply milk under the Definitely Devon brand through a licensing deal.
Chief executive Robert Wiseman said: “This acquisition will enhance our existing operations and efficiencies in the South West of England.
“It complements our planned expansion in this area with our proposed custom built dairy in the Taunton area.”