On Nov. 30, McGregor took to Twitter to announce the arrival of his latest child, a boy.
"My baby boy is born! Mammy and baby doing amazing, 8.1lbs of prime Irish double champion beef!" he tweeted. He also shared several images of the child, including one where he's holding him up in the air.
In one image it appears as though Devlin is breastfeeding and McGregor is cradling the two. He wrote on Instagram, "Another chunky healthy boy into the world. Dee you are my hero."
This is the fourth child for the pair having already welcomed Conor Jr., Croia and Rian. On Wednesday night he announced that the birth was coming, teasing his fans with a photo of the couple.
"Up early tomorrow to bring our new baby boy in to this world, say a prayer for us! Let’s go Mammy," he wrote.
McGregor is reportedly under investigation by the Irish Police for his tweets surrounding the riots in the country last week. He's being accused of "hate speech" after several tweets appear to support a violent reaction to a political issue.