The 34-year-old actress will be the emcee at the event in Oslo, Norway, which will celebrate the Organisation for the Prohibition of Chemical Weapons, reported Contactmusic.
The leaders of the agency received the honour earlier this month.
While the performers for the December 11 concert have yet to be announced, the event usually attracts some of the world's biggest stars Paul MCCartney, Rihanna and Tony Bennett , who have all attended in the past.