The Fiji Rugby Union said the decision was "a groundbreaking development for Fijian rugby, to take fans on a unique journey across the Northern Hemisphere" but is likely to be due to the greater earning potential of hosting the matches in Britain than on the Pacific island.
The Welsh Rugby Union, in also announcing the venues, said Wales at Cardiff City Stadium on July 4 was "an unprecedented opportunity for Fiji Rugby to generate significant commercial returns".
Fiji also host England at Everton's new Hill Dickinson Stadium on July 11 and their last clash is against Scotland at Murrayfield in Edinburgh.
The new competition was unveiled last November and pits northern and southern hemisphere countries against each other in two separate windows in July and November.
The competition, designed to give more purpose to the Test schedule, will conclude with a finals weekend from November 28-30 at Twickenham in London where all 12 nations will chase a placing.
The deciding clash will be between the top-ranked northern and southern hemisphere sides.
Argentina, Australia, Fiji, Japan, New Zealand and South Africa all host three matches against European opposition in July and travel north in November to play three away games in England, France, Ireland, Italy, Scotland and Wales.
Fiji will visit France, Ireland and Italy in their November fixtures.
Australia will play their home Southern Series in Sydney (v Ireland, July 4, Allianz), Brisbane (v France, July 11, Suncorp) and Perth (v Italy, July 18, HBF Park).
Monday's confirmation of venues means England will travel 25,000 miles, the equivalent of flying around the globe, in just over a fortnight in July.
After playing South Africa in Johannesburg they meet Fiji in Liverpool a week later then visit the small Argentine city of Santiago del Estero to take on the Pumas.
Points will be awarded for each result -- four for a win, two for a draw and a bonus point for scoring four tries or more, or losing by fewer than eight points -- which will then determine the pairings for the finals weekend.
NATIONS CHAMPIONSHIP
Southern Series
July 4: Argentina v Scotland, Australia v Ireland, Fiji v Wales, Japan v Italy, New Zealand v France, South Africa v England
July 11: Argentina v Wales, Australia v France, Fiji v England, Japan v Ireland, New Zealand v Italy, South Africa v Scotland
July 18: Argentina v England, Australia v Italy, Fiji v Scotland, Japan v France, New Zealand v Ireland, South Africa v Wales
Northern Series
November 7-8: England v Australia, France v Fiji, Ireland v Argentina, Italy v South Africa, Scotland v New Zealand, Wales v Japan
November 14-15: England v Japan, France v South Africa, Ireland v Fiji, Italy v Argentina, Scotland v Australia, Wales v New Zealand
November 21-22: England v New Zealand, France v Argentina, Ireland v South Africa, Italy v Fiji, Scotland v Japan, Wales v Australia
Finals weekend (Twickenham), November 28-30:
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