The billionaire entrepreneur announced on Tuesday (1 December) that his wife Priscilla Chan had given birth to their daughter, Max. and to celebrate her arrival, the couple penned a heartfelt letter vowing to give away 99 per cent of their Facebook shares to charitable causes over their lifetime.
Mark explained via his Facebook page that the couple wanted to make the world a better place for their daughter to grow up in, so would be donating the money - around $45 billion - to the Chan Zuckerberg Initiative.
He said: "Priscilla and I are so happy to welcome our daughter Max into this world! For her birth, we wrote a letter to her about the world we hope she grows up in.
"It's a world where our generation can advance human potential and promote equality -- by curing disease, personalizing learning, harnessing clean energy, connecting people, building strong communities, reducing poverty, providing equal rights and spreading understanding across nations.
"We are committed to doing our small part to help create this world for all children. We will give 99% of our Facebook shares -- currently about $45 billion -- during our lives to join many others in improving this world for the next generation. Thank you to everyone in this community for all your love and support during the pregnancy. You've given us hope that together we can build this world for Max and all children."
Their letter began: "Your mother and I don't yet have the words to describe the hope you give us for the future. Your new life is full of promise, and we hope you will be happy and healthy so you can explore it fully. You've already given us a reason to reflect on the world we hope you live in. Like all parents, we want you to grow up in a world better than ours today."