The event aims to protect children amid conflict that spans the world.
The focus this year for world leaders attending: how to end the war in Ukraine.
Madonna's post acknowledged how the leaders will collaborate on returning over 19,000 children torn from their families and deported to Russia.
Nearly 90 countries will be in attendance.
Moscow has not been invited but says it would not have attended anyway.
Vice President Kamala Harris will be there as part of the U.S. delegation.