"We are delighted to be welcoming Fiji and Samoa to council, two unions who have contributed so much to the game," World Rugby chairman Bill Beaumont said in a statement.
"The Pacific Islands are unique, immersed in rugby heritage, and I know that the unions will bring excellent insights and make strong contributions on council."
World Rugby's 49-member council oversees the strategy of the game and selects the hosts of Rugby World Cup tournaments.
The Pacific Island nations previously had only a share of the voting rights on the council through Rugby Oceania, which represents 12 nations from the region, including powerhouses New Zealand and Australia.
Rugby Oceania had just two votes, while New Zealand and Australia are amongst 10 nations -- the members who play in the Rugby Championship and Six Nations -- that have three votes each.
World Rugby has long argued that Pacific Island nations needed to implement better governance and administrative procedures before they could join the council as independent members.
Both Fiji and Samoa were denied seats on the council two years ago until they improved their governance.
"This shows that the model is in place, the pathway is in place and the door is open to other unions who aspire to have a seat on council," Beaumont added.
"We encourage all unions to take inspiration from Fiji and Samoa, review their governance and strive to achieve the required criteria."
(Reporting by Greg Stutchbury in Wellington; Editing by Nick Mulvenney)
