The prior two-weight UFC winner dropped the information Twitter instantly after Amanda Nunes defeated Felicia Spencer to keep her featherweight title at UFC 250 at Las Vegas.
McGregor posted an image of himself as well as his mum celebrating among his world title wins as he announced that he was hanging up his gloves.
He tweeted: “Hey guys, I have decided to retire from fighting. Thank you for the incredible memories! What a ride it has been!
“Here Is an image of my mom at vegas and myself post among my world title wins! Decide on the house of your dreams Mags I adore you! Anything you need it is yours.
And last year retirement’ neglected to adhere as McGregor Returned to knock Donald Cerrone within 40 minutes.