Manchester United have announced the signing of Chelsea's Mason Mount, who has signed a five-year contract with a one-year option.

The Planet Sport understands the fee agreed for the 24-year-old England midfielder is an initial £55million.

Mount - who came through the ranks at Chelsea and made 129 Premier League appearances for them, scoring 27 goals and providing 22 assists - said in a statement from United: "It's never easy leaving the club where you grew up, but Manchester United will provide an exciting new challenge for the next phase of my career.

"Having competed against them, I know just how strong a squad it is that I'm joining, and I can't wait to be part of this group's drive to win major trophies."

Mount, a Champions League winner with Chelsea in 2021, added: "Everyone can see that the club has made big steps forward under (United boss) Erik ten Hag.

"Having met with the manager and discussed his plans, I couldn't be more excited for the seasons ahead, and am ready for the hard work expected here.

"I am hugely ambitious; I know how amazing it feels to win major trophies and what it takes to do it. I will be giving everything to experience that again at Manchester United."

United football director John Murtough said: "Mason is an extremely intelligent footballer and has so many fantastic technical qualities that will significantly add to our squad.

"We have admired his talents for a long time, so we are delighted that he has chosen to take the next steps in his career here at Old Trafford.

"His style of play and attributes are a perfect fit for this squad, and we all believe that he will only improve further working with Erik ten Hag and his coaching staff.

"Mason himself is a world-class player but he also has the ability to improve the players around him through his game intelligence and tactical awareness.

"We were particularly impressed by his strong desire to join United, and his thirst for further success, as we push to drive up our performance levels next season and beyond."

Mount spent 18 years with Chelsea, making his first-team debut in 2019 after loan spells with Vitesse in the Netherlands and then Derby.

He posted a farewell message to Blues fans on Instagram in which he said: "Hi Chelsea fans, given the speculation over the last six months this may not come as a surprise to you, but it doesn't make it any easier to tell you that I've made the decision to leave Chelsea.

"I feel you deserve more than just a written statement, so I wanted to tell you directly how grateful I've been for all of your support over the last 18 years.

"I know some of you won't be happy with my decision, but it's what's right for me at this moment in my career.

"I joined Chelsea when I was six years old and we've been through a lot together. Winning the Youth Cup, my Player of the Year awards, the Super Cup, the Club World Cup and of course that unforgettable night when we won the Champions League.

"I want to say thank you to the academy, Jim and Neil for being so influential to me from such a young age. The managers I've worked under, Frank (Lampard), Thomas (Tuchel) and Graham (Potter), the backroom staff, the unsung heroes of Cobham, all of my team-mates over the years that have become my brothers.

"My family for the continuous love and support and most importantly you guys for sticking with me throughout. Wish you all the best."

Mount has made 36 England appearances, which includes helping the team reach the European Championship final in 2021 and playing at last year's World Cup in Qatar.

Mason Mount signs five-year contract with Manchester United