"I also travel quite a bit for the job I do, so I've included a wee momento from my last trip. Not too many people have these, but I wanted to share mine."
The Apec pin was given to Ardern when she attended the economic forum last month, along with other world leaders including US President Donald Trump.
The book, Goodnight Stories for Rebel Girls, features 100 bedtime stories about the lives of 100 women from the past and present, illustrated by women artists from around the world.
Ardern wrote in the inscription that the book belonged to "two amazing girls who can do anything they set their minds to".
The Prime Minister opened her own Secret Santa gift on Facebook Live last night.