Hannah Richardson took part in an event commemorating the 30th anniversary of the Convention on the Rights of the Child at the Palais des Nations in Geneva on Monday.
The Children's Parliament said the teenager, from East Lothian, was the only child from the UK to participate in the event on Monday, alongside young representatives from Switzerland, Mexico, Canada and the Philippines.
The teenager has been working with the United Nations Committee on the Rights of the Child as part of a global children's advisory team.Hannah, a member of the Children's Parliament, said she loved being part of the event.
She said: "I loved meeting the girls from the other countries - I was surprised it was all girls.
"I really enjoyed looking at the Committee's exhibition - I loved the giant globe with all the different flags on countries that have pledged their renewed commitment to the United Nations Convention on the Rights of the Child.
"I was very nervous for speaking at the event but I plucked up the courage and I now feel very happy and proud of myself."Last year Hannah become the youngest moderator, aged 12, in a United Nations discussion on children as defenders of human rights.
On Monday she gave input during one of the panel sessions discussing the relationship between children's rights and the environment, drawing on her experiences in StreetsAhead Tranent, a local community planning project in her home town, and the social and environmental impacts it has had.
Cathy McCulloch, co-director of the Children's Parliament, said: "We are so proud of Hannah. The youngest person in the room and the toughest spot at the end of a long formal day but she smashed it.
"Everyone made a beeline for her at the end to congratulate her. And she's ready for more."