The women's Rugby World Cup will expand from 12 to 16 teams from 2025.
The news follows increasing calls for the event to be expanded, with women and girls now accounting for 28% of the global playing population.
Since 2006 there have been 12 teams split into three pools, including the upcoming 2021 Rugby World Cup in New Zealand.
World Rugby chairman Bill Beaumont called the decision a "milestone moment" for the women's game.
The decision comes too late for the 2021 Rugby World Cup which has already staged its pool draw.
However, there will be the addition of quarter-finals in New Zealand after previous tournaments saw teams progress straight from the pool stage to the semi-finals.