Harrison (24) has spent the last three seasons on consecutive loan deals at Leeds United, including cementing a place as a regular starter during their first season back in the Premier League last campaign.
But the Whites had never made the move permanent- until now.
A report from the Manchester Evening News suggests that the winger will become a full-time Leeds United player this week.
The fee "could reach £15 million" if certain conditions are met, but details of the financial aspects of the transfer are currently thin on the ground.
Manchester City have a long history of inserting sell-on clauses when selling fringe or CFG players who are yet to reach their prime, including Borussia Dortmund winger Jadon Sancho.
City have a reported 15% sell-on clause in the agreement with Dortmund for Sancho, who is expected to join Manchester United this summer for a lofty fee.
And with Harrison getting better by the season, it's likely that Manchester City would try to secure themselves a slice of the action should the Englishman go on to earn another big move.
Players like Kelechi Iheanacho, Angeliño and Douglas Luiz have also been sold by Pep Guardiola's side with buy-back clauses in their agreements, allowing the club to bring the player back for a set fee should they wish.
It's not clear yet whether Harrison will be given the same treatment, but that could be something for City fans to keep an eye on.
Harrison's senior career began at MLS side New York City FC, sister club to Manchester City. He was signed by the Etihad club and started his time in English football with a disappointing loan spell to Middlesbrough, but the second time turned out to be the charm as he quickly became a fan favourite with the Leeds faithful.
To date, Harrison has played 126 times for Leeds, scoring 18 times.
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