The Whites academy graduate has penned a six-year deal at the Etihad, and leaves Elland Road for an initial fee of £42 million, which could in turn rise to as much as £50 million in the future.
And while Leeds fans will undoubtedly be disappointed to lose such a key player with such strong ties to the club, they will, at least, have plenty of fond memories to look back on.
From his early days in the first team and Marcelo Bielsa’s transformative on his career, to promotion back to the Premier League and England recognition, Phillips has come an awful long way in a relatively short period of time.
With that in mind, look back on some of his best moments below...
1. Early days
Phillips made his debut against Wolves in the Championship in April 2015, and would go on to play an increasingly important role for Leeds from that point onwards.
2. Fan favourite
A lifelong Leeds fan who was on the books from the age of 14, Phillips became a fan favourite at Elland Road.
3. The Bielsa Revolution
With the arrival of Marcelo Bielsa came a slight change in position for Phillips. Now playing in a deeper role, the midfielder bloomed, and Leeds would go on to end a 16-year absence from the Premier League.
4. Leeds through and through
Phillips’ positive presence at Leeds extended beyond the pitch, with the midfielder always proving popular among supporters.
5. Premier League star
Phillips made the transition to life in the top flight with ease, and Leeds made their mark on the division from their very first game back - a pulsating 4-3 defeat against Liverpool at Anfield.
6. Occasional goalscorer
With 14 goals in 234 games, Phillips was hardly prolific for Leeds, but when he did find the back of the net it clearly meant a lot to the local lad.