Third generation: Jim Carrey's daughter Jane has given birth to her first child
The actor's 22-year-old daughter Jane gave birth to son Jackson Riley Santana in a Los Angeles hospital yesterday.
The proud granddad posted a photo of the newborn on his Twitter micro-blogging page.
The baby weighed in at a healthy 7lbs, 11ozs and mother and baby are said to be doing well.
Excited granddad Jim wrote: 'Jackson Riley Santana, My Grandson, Born today! This is what 7lbs.11oz. of California dynamite looks like!'
Jim's girlfriend Jenny McCarthy has dubbed herself an honorary grandmother.
She wrote on her Twitter: 'Yes, I'm a grandma! Beautiful healthy baby boy. Dr jay Gordon is the paediatrician. Thank god! Jackson is in great hands.'
Baby Jackson is the first child for Jane and her husband Alex Santana, who married last November.
Ahead of the birth, Jane said she was relieved she was having a boy because she has always felt more comfortable around males.
She told People magazine: 'I’m excited about it because I never really got along with girls growing up.
'I was a little afraid that if it was a girl that she would not like me, you know? So I’m very happy about the boy.'
Jane's mother is Jim's ex-wife Melissa Womer, who he divorced in 1995.
Introducing baby Jackson: Jim Carrey posts a photo of his hours old grandson Jackson on his Twitter page
Jane is a singer/songwriter, while her husband goes by the stage name Nitro with his rock band Blood Money.
She said in a recent interview she hoped to be able to balance motherhood with her musical career.
She said: 'I’ve always wanted to be a mother and I’ve always wanted to do music, so to have the two together, it’s just awesome. It’s a dream come true.'