The suspension will come into effect immediately, meaning that the 21-year-old will serve the first of his three-game ban in Tuesday night's Championship clash with Reading.
The ban relates to an incident that occurred during Villa's 1-1 draw with Wolverhampton Wanderers in the Championship at the weekend, where Grealish appeared to stamp on opponent Conor Coady during the first period.
Grealish did initially accept the charge, but thought that a three-game ban was excessive. The FA, though, rejected that claim and has issued a three-match suspension to the England Under-21 international.
"Aston Villa's Jack Grealish will serve a three-match suspension with immediate effect after he committed an act of violent conduct which was not seen by the match officials but caught on video," read a statement from the FA.
In addition to the Reading match, Grealish will also miss Villa's league games against Fulham and Birmingham City.