The new royal baby is already being showered with presents, including from New Zealand.
Their Royal Highnesses, the Duke and Duchess of Cambridge, welcomed a baby boy overnight.
A collection of New Zealand childrens' books and a blanket made of New Zealand wool will be sent to the baby, Ms Ardern told The AM Show.
The Prime Minister also added a personal gift.
"I've had a family member of mine whip together a personal gift... a white linen romper with a Buzzy Bee lining on it."
Ms Ardern revealed the mastermind behind the romper is her sister-in-law,
"She's an excellent sewer."
She said a note will be added to indicate the personal nature of the gift.
As to if she herself will receive a present from the royals, the Prime Minister laughed and said she wasn't expecting anything.
The name of the royal baby is yet to be revealed.