The move may have just ignited a new rivalry, as Royal Editor Chris Ship reports
The Duke of Sussex previously held the roles for five years and they are the first of his royal patronages to be redistributed.
The Sussexes were stripped of all their royal patronages in February 2021 after they confirmed they would not be returning as working members of the Royal Family.
Harry became patron of the RFU in 2016, taking over from the Queen who held the role for 64 years. He had previously been vice patron since 2010.
Kate wrote on Twitter: "I am so thrilled to become Patron of the @TheRFL and @EnglandRugby. I look forward to working with them across all levels of the games, and to cheering England on in what promises to be an exciting year for both sports!"Two fantastic organisations who are committed to harnessing the power that sport can have in bringing communities together and helping individuals flourish."
Kensington Palace said: “These new patronages, which have been given to The Duchess by Her Majesty The Queen, closely align with Her Royal Highness’ longstanding passion for sport and the lifelong benefits it can provide, both within our communities and on an individual level.”
Kate is a keen sportswoman and has particularly enjoyed tennis, hockey and sailing from a young age.
She is already Patron of The 1851 Trust, Sportsaid, the All England Lawn Tennis and Croquet Club and the Lawn Tennis Association.
Bill Sweeney, Chief Executive of the Rugby Football Union, said: “It is a great honour to welcome The Duchess of Cambridge as our Patron.
“Our aim is to enrich lives, introduce more people to rugby union, develop the sport for future generations and create a successful thriving game across the country.
“As rugby clubs have re-opened across the country, players, officials, and volunteers are celebrating being back in the game together, and we know the support of The Duchess will be greatly valued from our grass roots clubs and fast-growing women and girls’ game, right up to our elite Men’s and Women’s England teams."
Kate’s role as patron of the RFU has been announced just ahead of England’s first Six Nations clash against Scotland on Saturday.
It also sets up a fresh sporting rivalry between the Cambridges as Prince William is patron of the Welsh Rugby Union.
Ralph Rimmer, Chief Executive of the Rugby Football League, said: “We are truly honoured by the appointment of The Duchess of Cambridge as the Rugby Football League’s Royal Patron.
“We are delighted to welcome her as we prepare to host Men’s, Women’s, Wheelchair and Physical Disability Rugby League World Cups in England this autumn. Our sport’s history has been built on a commitment to tackling inequalities and we honour that through our focus on having a positive social impact well beyond the pitch.
“We look forward to working with The Duchess in the years to come, and I know all levels of our sport will welcome her to the Rugby League family.