The 2027 Rugby World Cup will be contested between 24 teams after World Rugby's council approved the expansions ahead of the 2023 final.
The change that will come into effect for Australia 2027 is intended to provide more qualification opportunities for emerging nations as well as regional competitions.
Further details of the revised format for the group stage will be announced at a World Rugby press conference on Tuesday afternoon.
A new bi-annual international competition is also to be launched in 2026, comprising of two divisions of 12 teams with promotion and relegation commencing from 2030.
The matches will take place in the July and November international windows.
