The "Roar" singer attended the UNICEF Snowflake Ball in New York City last night, where she was named one of the organization's goodwill ambassadors.
"Guys! I am SO honored to become a @UNICEF Goodwill Ambassador today! I am #unconditionallyUNICEF: http://uni.cf/katyperry @voicesofyouth," she tweeted yesterday before the event.
Katy arrived at the event in a Naeem Khan cranberry-colored velvet gown and gold embroidered shawl, but changed into this giraffe-skin dress for her performance.
"Katy Perry is already a champion for children, and we look forward to hearing her 'roar' on behalf of UNICEF," the UNICEF Executive Director said in a statement. "We are delighted that she is joining us as UNICEF's newest Goodwill Ambassador and lending her remarkable voice to amplify the voices of children and young people around the world."
The singer's outreach efforts will be focused on encouraging children and adolescents to speak out about the issues they face.
Other guests at last night's event included Christina Ricci, Katie Couric and Jenna Bush Hager.