Phillips, 26, came through the youth ranks at hometown Leeds and made his debut at the age of 19 in 2015.
He was converted from an attacking midfielder to a deep-lying playmaker by former manager Marcelo Bielsa and, after rejecting a move to Aston Villa, shone as Leeds won promotion back to the Premier League after a 16-year absence in 2020.
He earned his first England cap in September of that year and went on to start every game at Euro 2020, where Gareth Southgate’s side reached the final.
His final season at Leeds was disrupted by injury but ended on a positive note as relegation was avoided on the final day of the campaign.
Phillips admitted his decision had been a difficult one but now hopes to take his game to the next level.
“I have always loved Leeds and it is all I have ever known,” he said. “To come here is a big decision for me. It is a decision that took a lot of thinking about.
“It was just more the fact that I wanted to experience something different, how different teams work and how the fanbase works as well.
“I think I am pretty suited to playing in big games. I haven’t experienced many of them but hopefully this season I will do.”
And with the move confirmed, we have looked at the 13 largest big-money departures from Leeds in the Premier League era...
9. Robbie Keane - £7m
Leeds agreed to sell the Irish striker to Tottenham at the end of August 2002 having signed the forward for £12m in in 2001. Photo: Getty Images
10. Alan Smith - £7m
The Leeds-born player left his hometown club for bitter rivals Manchester United following the Whites' relegation at the end of the 2003-04 campaign. Photo: Getty Images
11. Ronaldo Vieira - £7m
Leeds accepted a bid for the player from Serie A side U.C. Sampdoria in July 2018, bringing an end to his two-year stay at Elland Road. Photo: Getty Images
12. Lewis Cook - £6m
Bournemouth signed the Leeds academy graduate in July 2016 after he had made 80 appearances in two seasons for United. Photo: Getty Images