Super agent Raiola, who represents Paul Pogba and Zlatan Ibrahimovic, counts Sandler as one of his clients.
The 21-year-old centre-back played 30 times for PEC Zwolle in the Eredivisie which has been enough to catch City’s eye.
The reigning Premier League champions announced the arrival of the Dutch Under-20 international today.
A City statement read: “Manchester City are delighted to confirm the signing of Dutch defender Philippe Sandler.
“The 21-year-old, a product of the Ajax youth system and capped for his national U20s side, has moved from Eredivisie team PEC Zwolle.
“At 6ft 2in tall Sandler is a commanding presence at centre-back, while also comfortable in a holding midfield role.
“Everyone at City would like to welcome him to the Club.”
Sandler came through the ranks at Ajax before moving on to their Eredivisie rivals and is likely to be one for the future at the Etihad Stadium.
City also confirmed the departure of Kosovo midfielder Bersant Celina to Championship side Swansea.
The 21-year-old made four first-team appearances during the 2015/16 campaign but was then loaned out to FC Twente and Ipswich.
Celina has signed a four-year deal with the Swans as new manager Graham Potter builds a squad he hopes to secure an immediate return to the top-flight.
Manager: Pep Guardiola
Position last season: Champions
Ground: Etihad Stadium
Players In: Riyad Mahrez (Leicester, undisclosed), Philippe Sandler (PEC Zwolle, undisclosed)
Players Out: Pablo Maffeo (Stuttgart, undisclosed), Yaya Toure (released), Will Patching (Notts County, released), Ashley Smith-Brown (Plymouth, undisclosed), Matt Smith (FC Twente, loan), Jacob Davenport (Blackburn, undisclosed), Manu Garcia (Toulouse, loan), Angus Gunn (Southampton, undisclosed), Isaac Buckley-Ricketts (Peterborough, undisclosed)
Key Man: Kevin De Bruyne
Chances: After dominating the Premier League last season, City have already shown there is no room for complacency by breaking their transfer record to sign Riyad Mahrez. Pep Guardiola’s past record indicates he will not relent in his pursuit of success and City will look to start in the same exhilarating fashion where they left off. The onus is on rivals to stop them.