John Stamos says ''all [he's] ever wanted'' is to be a father.

The 54-year-old actor celebrated his first Father's Day on Sunday (17.06.18) after welcoming his son Billy - whom he has with his wife Caitlin McHugh - into the world two months ago, and in an emotional Instagram post to ring in the occasion, the star gushed about his journey into fatherhood.

Posting a photo of himself and Billy - which also marked the first time the star has shown the tot's face on social media - the 'Fuller House' star wrote: ''My first Father's Day means that I don't have to hand a kid back to the parents when someone yells cut. It means when people ask me if I'm a father, I don't have to use the goofy line, ''No, but I play one on TV'' My first Father's Day means that from this day forward-- I will start to look my age (and older) Most importantly, it means that for the rest of my life, I'll always be known as someone's dad. And that's all I ever wanted.

''Happy Father's day. (sic)''

And John could be set to spend next Father's Day as a father of two, after he and Caitlin revealed they are already thinking about expanding their brood.

When asked if they want more kids, Caitlin said: ''As soon as I can!

''Right now, Billy is extremely spoiled and we need to share the love, he's gotta share some of those toys and all the things that have been given to him. He needs [siblings] to keep him grounded. If he's the only one, he'll get way too much love because there hasn't been a child on either side of our family in quite some time.''

John will have no problems with another tot in the house though, as Caitlin also admitted the actor is a natural when it comes to parenting.

She said: ''He used to say he's not going to change any diapers... and he's changed so many diapers! He totally doesn't mind it. It's beautiful seeing [John] with Billy. It all feels so right. It feels like this is the way it should've always been.

''He comes so naturally to fatherhood and I love watching it. I stare at the both of them all the time beaming. [John is] 100 per cent full-on active and fantastic ... He's perfect, he's a perfect father. I can't wait to give him more [kids].''