From 2020, the current June international window will move to the first three weeks of July to allow Super Rugby to be completed prior to the start of the test programme.
There will also be a minimum of a 39 percent increase in matches between top and second-tier nations between 2020 and 2032, including a commitment from England and France to play in the Pacific.
"Agreement on an optimised global calendar that provides certainty and sustainability over the decade beyond Rugby World Cup 2019 represents an historic milestone for the global game," World Rugby Chairman Bill Beaumont said.
The November international window, when Southern Hemisphere teams head north, will start a week earlier to give players a longer off-season break.
And the Rugby World Cup will also begin a week earlier from 2023.
Southern Hemisphere teams have committed to hosting tier-two teams in July, while Georgia and Romania will also entertain Six Nations sides in that window.
Six Nations sides have also guaranteed they will host a minimum of six matches against second-tier teams in November.
"This agreement has player welfare and equity at heart, driving certainty and opportunities for emerging rugby powers and laying the foundations for a more compelling and competitive international game, which is great for unions, players and fans," Beaumont said.
"This process has been complex and there was no silver bullet. Compromise has been achieved by all stakeholders in the spirit of collaboration," he added.
England has previously toured Fiji in 1988 and 1991, winning both tests, but have never played an international in Samoa or Tonga.
France defeated Fiji in Suva in 1998 and Samoa in Apia a year later, but were beaten 20-15 by Tonga in Nuku'alofa in 1999.
Samoa will host Wales in Apia this June and were to play in Tonga, but that match will now be hosted at a neutral venue because Teufaiva National Stadium in Nuku'alofa is not up to international standard.
Photo: AFP England have hosted Fiji three times since 2012 but last played in the Pacific in 1991.