The transaction is expected to be completed in the first half of 2016. It includes United Drug and United Drug Sangers, wholesale operations across the Republic of Ireland and Northern Ireland.
McKesson will also acquire TCP, a home healthcare provider in the Republic of Ireland; and MASTA, UDG’s travel healthcare business based in the UK.
As part of the acquisition, over 1,000 UDG employees will join McKesson.
The acquired operations will become part of McKesson’s international pharmaceutical distribution and services business.
It will be led by Marc Owen, chairman of the management Board at Celesio, the European business within McKesson’s distribution solutions segment.
Owen said: "The acquisition of UDG’s pharmaceutical distribution, home and travel healthcare businesses in Ireland and the UK, will strengthen our position in the industry.
"We have made this investment as part of our growth strategy which leverages the positive trajectory of the wider healthcare sector in Europe. This acquisition will also complement our broader portfolio of assets in both Ireland and the United Kingdom."
McKesson has recently agreed to acquire 281 pharmacies operated by Sainsbury’s in the UK.
McKesson and Albertsons have signed a five-year distribution agreement to include the sourcing and distribution of both branded and generic pharmaceuticals, starting April 2016.
Albertsons’ network of about 1,700 pharmacies in their 2,200 stores across US will benefit from the scale and strength of McKesson’s OneStop generics program and efficiency of the company’s daily direct-to-store service model for pharmaceutical products.