Seems Colin Farrell is taking Conor McGregor at his word -- saying he supports his fellow Irishman's decision to retire from MMA ... and wishes him well in his future outside the octagon.
Farrell was leaving "Good Morning America" where he was promoting the new "Dumbo" flick when we asked if he REALLY believes we've seen the last of The Notorious in the UFC.
"Everyone can do what they want man," Farrell said ... "Everyone's gotta follow their hearts."
Colin's been a huge McGregor supporter for years -- raving about Conor back in 2015 as one of the most "phenomenal" athletes on the planet .