Lactalis said it had done a deal with private equity group BC Partners to buy Galbani, which makes a range of Italian cheeses, including mozzarella and ricotta, under the Santa Lucia, Galbani and Bel Paese brands.
The amount was not disclosed, although BC Partners had valued Galbani at €1.1bn on its website.
Lactalis said it planned to launch Galbani's range of cheeses across its markets. "The creation of a European-wide business in Italian cheese will enable us to develop these speciality products in all markets where Lactalis and Galbani are present," it said.
Galbani already gets 23 per cent of its €1.3bn annual sales from exports. The firm processes around 800m litres of milk across three cheese factories in northern Italy.
The move by Lactalis adds weight to its position as Europe's number one cheese maker. It already owns big French brands such as Société Roquefort, President and Brie de Meaux.
The deal comes as the latest in a flurry of ventures by Lactalis, including a fresh dairy joint-venture with Nestlé and a co-operation agreement with Dutch dairy Friesland Foods in Germany.
Nestlé and Lactalis together will form Europe's second biggest fresh dairy firm behind France's Danone.
A Document from Lactalis regarding its views on buying UK processor Dairy Crest were passed to the UK's Guardian newspaper in December. The document reportedly said that Lactalis could get 60 per cent of the UK cheese market by taking over Dairy Crest.
Lactalis, however, said it was not looking to buy Dairy Crest, while the British firm said it had received no approach and denied it was in negotiations with Lactalis.