The England international had seemingly committed his future to Villa but has now completed a switch to the Etihad.
The move comes just days after the 25-year old had released a passionate statement through Aston Villa's official site, pledging his loyalty to the Midlands club and speaking of his excitement ahead of the new campaign.
In what will be a tremendously difficult pill to swallow for Villa fans, Delph has now signed a five-year deal with last season's Premier League runners up.
An £8 million buy-out clause was inserted into Delph's new contract, signed in January, and Manchester City activated it last week but had appeared to lose out on the chance to sign him after discussing personal terms. Since then, however, there have been further talks and the former Aston Villa captain has been persuaded to make the switch.
The Delph heartbreak follows news that Liverpool will meet Christian Benteke's £32.5 million release clause, as per talkSPORT, in what has been a tough week for the Villa faithful. Twitter was predictably awash with reaction and below is a selection from both sets of fans:
Delph and Benteke both gone....get over it and just replace them #avfc— Matty (@MattyGriffi) July 17, 2015
Officially a selling club- Milner, young, downing, Barry, Delph, benteke just to name a few. No ambition at #avfc— Gemma Whitehead (@gem10whitehead) July 17, 2015
Can I take back how much I respect Fabian Delph after having a medical with City? So much for the loyalty I talked about last week...— Andrew Woodhouse (@woody2goody_uk) July 17, 2015
@GJ_Thomas Handled really poorly by both Delph and the club but don't blame him for wanting more than finishing lower mid-table every year.— Tom Nightingale (@tdnightingale) July 17, 2015
I like Delph. A younger, similar Fernandinho and should do well for us. 8m is nice too.— Paul Sunderland (@PaulSunderlandd) July 17, 2015
Fans and media will demonise Delph, but maybe it's @AVFCOfficial who've broken promises to him and he's taken a great opportunity to move on— Garry Harding (@SuperBlue623) July 17, 2015
The little fish has decided to go into the big pond! #Delph— eddie brownhill (@EddieBrownhill) July 17, 2015
Delph when he realises he'll be playing with Yaya Toure instead of Tom Cleverley https://t.co/cFdFqiDYeL— YourMCFC (@YourMCFC) July 17, 2015
And the whole confusing saga was neatly summed up by Paddy Power with the following tweet: