The adorable foursome matched in blue for the occasion with Kate Middleton wearing a suit by Princess Diana's favourite designer, Catherine Walker.
The Duchess, who is currently pregnant with her third child, wasn't yet showing her baby bump when the photo was shot earlier this year by royal photographer, Chris Jackson.
In addition to revealing their new portrait, Prince William and Kate also announced that Princess Charlotte will be starting nursery school in January 2018.
The two-year-old will attend Willcocks Nursery School in London which is "delighted" to accept the Princess as a new student.
"We look forward to welcoming Charlotte to our nursery in January," Willcocks Nursery School said in a statement.
We don't know about you but we can't wait to see Princess Charlotte's first day photos, if George's are anything to go by, they're bound to be ridiculously cute.