Secretary-General Ban Ki-moon presented the actor and filmmaker with the U.N. Correspondents Association's Global Citizen of the Year award for humanitarian endeavors.
Cage said his role will be "to shine a spotlight on the need for global justice."
The Amnesty International advocate has donated $2 million to establish a fund to help former child soldiers and led a campaign around his film, "Lord of War," to raise awareness about international arms control.
The secretary-general also presented a Global Citizen of the Year award to William Roedy, chairman of MTV Networks International, for his work to combat HIV and AIDS.