The 47-year-old's producer wife Susan gave birth to their son Exton Elias in Febuary, reported Femalefirst.
The "Iron Man" star got into trouble with his spouse because he accidentally revealed the sex of their child during an appearance on The Tonight Show With Jay Leno.
The presenter of the show, Jay Leno persuaded Downey Jr to share the newborn's images with the audience despite his wife's instructions to keep it under wraps.
"No, I can't, I would be in huge trouble. I mean I want to, but I have to exercise a little restraint I am sorry..I mean, if you want me to I will," Downey Jr hesitated but finally succumbed.
The first shot showed his partner, wearing an Exton nameplate necklace, cuddling with the infant, while a second photo captured the little boy lying on his back in a striped top and orange pants.
The movie star said the boy was named after his wife's "eccentric" great uncle, Jay Exton.