Golf makes its return to the Games for the first time since 1904 in Brazil and Northern Irishman McIlroy, 25, who was eligible to represent either GB or Ireland, has opted for the latter.
"I've been thinking about it a lot," McIlroy told a press conference ahead of the Irish Open at Fota Island. "I don't know whether it's been because the World Cup has been in Brazil and I've been thinking a couple of years down the line.
"Thinking about all the times that I played as an amateur for Ireland and as a boy and everything, I think for me it's the right decision to play for Ireland in 2016."
McIlroy had previously spoken of being in a difficult position regarding his allegiance and considered not playing at the Games at all.