The International Rugby League announced Monday that the 2030 World Cup will be staged across the United States and the Pacific, bringing the tournament to North America for the first time.
The men's competition will grow from 10 teams to 12, while the women's tournament will expand from eight teams to 10.
Fixtures will move between alternative cities over five weekends, featuring three group-stage games, a semi-final and a final.
The United States, last represented at the men's tournament in 2017, will have to qualify rather than receive an automatic place.
The NRL and Australian Rugby League Commission will carry the risk of staging the event, and Grant said the NRL's capability made it an ideal partner.
He cited the NRL's games in Las Vegas and plans for a global round as evidence of its ability to deliver.
The IRL had also considered Europe for 2030 as the NRL approaches an investment deal in Super League.
Grant described a 2034 tournament across Europe and North America as his "aspiration".
Discussions are underway about elevating Tonga and Samoa from tier two to tier one.
Grant said consultation would ensure there were no unintended consequences and clarify what promotion would mean.
He also defended eligibility rules allowing players to represent a country through a great-grandparent, rather than only a grandparent, saying the public deserved to see those players compete internationally.