An official announcement is expected to come ahead of the rugby league World Cup in October.
The transition makes sense, considering Kate herself is a keen fan of rugby.
In an article written for Vanity Fair in 2014, the duchess' sister Pippa Middleton revealed just how important rugby was in their household growing up.
"Rugby was a big thing in our family, and the focal point was international matches... We'd plan our weekends around the matches... If we lost, my dad would be in a state of despair for the rest of the afternoon, as if he'd actually lost the game himself," Pippa said.
Meanwhile, as President of the Football Association, Prince William is also keen on sport. And it seems the parents have passed on the gene to their eldest son, George.
In June, The Duke and Duchess of Cambridge took the little heir to see England play in the 2021 Euros (the European Football Championship) multiple times.
WATCH: Prince George, Prince William & Duchess Catherine celebrate at the EURO 2020 final (Article continues after video)
And while the royal trio couldn't contain their excitement when England won against Germany, it was a different scene when the team lost the penalty shoot out to Italy in the finals.
But never fear, considering how big his parents are on sport (and Kate's new reported responsibilities), we're sure George will attend many more events where that came from - not to mention with prime royal seating.