Wines of Argentina, Wines of Chile and Wines of South Africa will run the tasting under the name The Beautiful South on September 11 and 12 at Olympia in west London.
The venue is the former home of the London International Wine Fair.
The generic bodies believe that by joining forces they can create “an event which has greater relevance to the UK and international trade” and is more cost-effective.
The three organisations have traditionally held separate UK tastings in the autumn.
The Beautiful South will exhibit wines by winery, though UK importers will be grouped together for convenience.
There will be “seeking representation” areas for producers from all three countries who do not have distribution.
The event will feature cross-country seminars and themed tastings, and all three organisations will bring in guests from key European export markets in addition to UK visitors.
Jo Wehring, UK market manager for Wines of South Africa, said: “This is a confident move by three wine-producing nations that are not afraid to stand together to meet the needs of the international trade.
“We are excited about the calibre of visitors we will attract by coming together and working in a way that is dynamic but has a solid strategy.”
Michael Cox, Europe director for Wines of Chile, added: “Three southern wine countries are breaking the mould with an innovative collaboration that aims to shake up the New World order. Fortune favours the brave.”
Andrew Maidment, European director for Wines of Argentina, said: “We are listening to the trade who have talked for years about taking a different approach to tastings.
“We aim to be fresher, more exciting and to provide an event which makes the best use of time for all involved.”
The group will be launching a website and releasing booking details shortly.