The Champion Lightweight posted a photo of his son sitting in the toy car Saturday on his Instagram account.
"You'd look good as a princess baby what's up hahah," McGregor wrote on the caption.
The 28-year-old Irishman has already dubbed his son as the next MMA star. 'Baby Notorious' was born on May 6 at Coombe Maternity Hospital in Dublin, Ireland.
McGregor has flooded his Instagram with photos of the youngster, saying he can already "land the left paw from anywhere." He also had his son pose for a photo with his UFC title belts, writing "let's go get some boxing ones now son," in reference to his fight with Mayweather.
Like dad, Conor Jr. has his own verified Instagram account with nearly 68,000 followers. McGregor also posted a photo of the duo Saturday from his porch. He was holding Jr. in that photo while standing shirtless under the bright sunlight.
"Happy Saturday," wrote McGregor, who has 13.8 million Instagram followers.
McGregor's long-awaited boxing bout against Mayweather was finalized this week for an Aug. 26 matchup in Las Vegas. The fight is expected to take place at T-Mobile Arena and will air on Showtime.
The bout will be at boxing's junior middleweight limit of 154 pounds.
Mayweather (49-0) is currently a -725 favorite to take the fight, according to BetOnline.ag.