In the clip, Meghan urges girls around the world to “keep asking questions, keep pushing forward, keep shining brightly.”
The clip also features a television report of Meghan as a child, in which she argues against gender stereotypes in advertising and stresses the importance of letter-writing and tackling social issues.
In the video posted Friday, Meghan says: “Every girl has potential. She has promise, she has the right to learn, the right to be heard, the right to play and to discover, the right to be exactly who she is.”
Also included is a clip from her speech to a United Nations conference in 2015, when the Duchess — then known as Meghan Markle — was an actress on US TV show “Suits.”
“It is said that girls with dreams become women with vision,” she says in the speech.
The UN declared International Day of the Girl in 2012, and it is observed every October 11.
CNN’s Max Foster contributed to this story.