UNICEF has appointed Millie Bobby Brown, the star of hit Netflix series "Stranger Things," as its youngest ever goodwill ambassador.

When the 14-year-old was asked if she had a message for world leaders, she told Reuters: "Listen to us. Youth is very powerful." 

As to her role for the United Nations children's agency, she said, "I want to raise issues about education and violence and ending bullying and ... making sure children have a safe environment and clean water. But I'm still learning what I feel passionate about."

Brown's appointment as a goodwill ambassador on Tuesday marked World Children's Day and came after she co-hosted UNICEF's 70th-anniversary celebrations in New York in 2016, interviewing David Beckham on stage.

Emmy-nominated Brown, who plays a girl with special powers who tries to help rescue a missing boy in "Stranger Things," has spoken out in the past against bullying and last year deleted her Twitter account after a slew of hate-filled comments. 

She pledged to speak out for millions of children and young people whose voices had been silenced, shine a light on issues that vulnerable children suffer around the world and make sure children know their rights and empower them.

Brown said she would use her platform, which includes more than 18 million followers on Instagram. She was also the youngest person to make Time magazine's list of the world's 100 most influential figures.

"In becoming a UNICEF goodwill ambassador, I share the title with a hero of mine – the late, great Audrey Hepburn, who once said: 'As you grow older you will discover that you have two hands, one for helping others and one for helping yourself,'" Brown told a news conference announcing her appointment.

"That's exactly what I intend to do," she said.