"We are excited by Australia's vision and passion to work with World Rugby to deliver an exceptional Rugby World Cup in 2027 and now 2029," Gilpin said.
Rugby Australia recently has faced tough financial times in a four-way contest for attention with rugby league, Australian Rules football and soccer.
In 2020 it posted a $US20 million deficit, partly due to the impact of COVID-19.
"Australia is a huge player on the international stage," Gilpin said. "We want Australian rugby to be strong, we want rugby here to be back to being a really strong sport for kids in Australia and this decade-long opportunity culminating in an Olympic Games (in 2032) with rugby sevens is a massive chance for that."
Rugby Australia chief executive Andy Marinos said the World Cups could generate between US$40 and $50 million for rugby.
"This is huge for us in terms of resetting our whole landscape," Marinos said. "Not only about the revenue you generate out of the event, it's about connecting with new commercial partners, re-engaging with broadcasters.
"We're living in an interesting age. The broadcast and digital world is going through seismic change. Events like this ... create a diversified offering. If we're smart from the outset, we can capitalize on it."