McIlroy is on a run of seven consecutive top-two finishes on the European Tour, following a runners-up finish in Abu Dhabi with victory at the Dubai Desert Classic.
The world No 1 is looking forward to featuring on March 19 having previously turned down invitations.
"I'm delighted to add the Arnold Palmer Invitational at Bay Hill to my 2015 playing schedule," McIlroy said.
"Mr Palmer is the father figure of modern golf, widening its appeal and bringing the game to a new audience. Every playing professional of my generation owes a debt of gratitude to Arnold Palmer."
Golfing legend Palmer said he was glad that McIlroy confirmed his participartion.
"I am very pleased that Rory is going to be playing here," Palmer said.
"I have talked to Rory about playing here, and it didn't work into his schedule in the past, but he told me that when it did work into his schedule that he would be here, and he is making good on his word," he added.