Warne will travel by helicopter from London to Cardiff before handing over the ball in the centre circle of the Millennium Stadium before the match between Liverpool and West Ham United.
"I'm told I'm the first Aussie in history to deliver the ball and being the 125th FA Cup it makes it even more special," Warne said in a statement from sports good manufacturers Mitre.
Leg-spinner Warne, the most successful wicket-taker in the history of Test cricket, is playing county cricket for Hampshire during the English summer.