McIlroy, looking visibly upset at a press conference ahead of an upcoming tournament, announced he had broken off his five-month engagement to tennis player Caroline Wozniacki just days after sending out wedding invitations.
The former world number-one ranked golfer said the high-profile split was "mutual and amicable" after confirming the relationship had ended because he realized he was not ready for marriage.
"There is no right way to end a relationship that has been so important to two people," he glumly said Wednesday.
This wouldn't be the first breakup for the pair, who got engaged on New Year's Day after more than two years together.
McIlroy called it off with Wozniacki in April last year — days after she posted a picture on Twitter showing him asleep and open-mouthed with his glasses on.
Friends of the pair said there was no way back and the tennis star was described as being "absolutely devastated."
In a brief statement issued through his Dublin-based communications consultants, McIlroy, said he was making the announcement publicly after talking to Wozniacki.
"The problem is mine," he said.
'The wedding invitations issued at the weekend made me realize that I wasn't ready for all that marriage entails.
"I wish Caroline all the happiness she deserves and thank her for the great times we've had."
Following the announcement, the golfer looked distracted as he attended a press conference at the Wentworth course in Surrey ahead of his latest tournament.
He said he wanted to get his head into golf but admitted it would be difficult on the back of a very public break-up.
"Obviously (it's) quite a difficult time for Caroline and myself, and I think the statement really said it all this morning," he said.
"It was mutual and amicable and we both thought it was the best for us, the best for both of us. Time to move on and I think I've said all that I need to say."