Howson has agreed a three-and-a-half-year contract with the Barclays Premier League club.
All that remains now is for the relevant paperwork to be rubber-stamped and Howson to recover from a knee injury, and the Morley-born playmaker will be free to make his City and Premier League debut.
The 23-year-old midfielder, who made the first of his 227 Leeds appearances against Barnet in 2006, had previously stated his desire to reach the top division with the club he has supported all his life and captained for the last two years.
However, with Leeds struggling to put together a convincing push for promotion - despite sitting a point outside of the play-off places - and with just six months remaining on his current deal, Howson has decided to take the option of "guaranteed" Premier League action.
"The reason (for leaving) is the Premier League," he told LUTV.
"I am going to a very good club with good support, but at the same time I know I'm leaving a club I've loved from being such a young boy. That's not going to change.
"Leeds has been a massive part of my life. But this is a great chance for me. This is the sort of chance that doesn't come around too often, and it's a chance I feel I have to take while it's there."
Howson, who has been at Leeds since he was six, is the latest in a long line of key players the Yorkshire club's fans have seen leave Elland Road over recent years.
Jermaine Beckford, Neil Kilkenny and Bradley Johnson all left after their contracts ran down, while Max Gradel and Kasper Schmeichel were sold a year out from their contracts' expiry dates.
The departure of Howson, though, has proved to be a tipping point for many fans, who used Saturday's 3-1 win over Ipswich as a chance to protest against chairman Ken Bates and a perceived lack of ambition and investment.
"It makes it harder when you see a reaction like that. You realise you mean something to them," Howson added.
"I was the club captain and from the area, but it was me that was still wanting to play in the Premier League and, from the club's point of view, I would have done the same thing if I were in their shoes."
Howson injured his knee against Millwall on December 3 and is currently working his way back to fitness, but new manager Paul Lambert is looking at the longer-term picture.
"I think he has been brilliant for Leeds - how he has played but also being their captain brings its own demands. It's a fantastic club, Leeds," he said.
"I think he can add goals to our midfield, which I think we need and he can do that. He'll get better as a player the higher the level he goes up.
"If he does that and everything goes well, he'll be a great player for us."
Leeds have strenuously denied that other players will be following Howson out of the club, with manager Simon Grayson saying talk that Scotland winger Robert Snodgrass - who Norwich bid for in the summer - had terminated contract negotiations was "rubbish".