Robert De Niro's youngest daughter is "pure joy".

The 80-year-old actor's little girl Gia - who he has with partner Tiffany Chen - turned one last month and enjoyed a "sweet" celebration with her family, with the proud father gushing about how much happiness she has brought to his life.

Asked if Gia had celebrated her birthday, he told 'Entertainment Tonight': "Yes, she did. She had a little cake, it was very nice, sweet.

"Well, she's pure joy, there's nothing about her, there's no judgment, there's no anything, she just is what she is and it's just pure joy for god sakes."

The 'Irishman' actor insisted his age won't mean he'll be slowing down any time soon.

He said: "I mean, I try to keep active in everything and yeah, what else am I gonna do?"

The 'Killers of the Flower Moon' star is also a father to Drena, 56, and Raphael, 47, with his first wife Diahnne Abbott, twins Julian and Aaron, 28, with ex-girlfriend Toukie Smith, and Elliot, 25, and Helen, 12, with ex-wife Grace Hightower and he previously gushed about how much he loves seeing his brood all together on family vacations.

He told People magazine: “The fact that they’d all be together is everything to me."

Asked what his favourite thing to do with his children is, he replied: “Just being together, taking trips to warm places."

The 'Meet The Fockers' actor has been imparting little pieces of wisdom his parents taught him about life to his children.

He said: “One thing I'd say to one of my younger kids is that there are things that I remember that [my parents, De Niro Sr. and Virginia Admiral] told me that you don't forget.

“Certain little truisms or whatever you want to call them.”

“Little examples of life saying, ‘If you do this, this is what you do. Always do this, do that.'

“I say, ‘You're going to remember what I just said to you, you're not going to forget it and it'll register with you and it will make an impact and a good one.

“So that I've found myself doing [that].”