Lee, 25, took up her role at a ceremony last week, attended by 400 young people at Leighton Hill Community Hall, in Causeway Bay. She will be leading Unicef's "Right to Play" campaign.
At the ceremony, the former Bishop Paschang Catholic School student shared her favourite childhood memories with the audience. "We weren't very rich, so we shared tricycles in the neighbourhood," said the cyclist, who was raised on the Lower Ngau Tau Kok Estate.
Lee said it was fun to spend time with her brother and neighbours, and even now some of them still ring her and invite her to go for a ride with them.
Article 31 of the Convention on the Rights of the Child states that children have the right to rest and play, and "to participate freely in cultural life and the arts". But Unicef is concerned that young people today spend too much time using gadgets and mobile games and are forced to attend too many extra-curricular activities.
Leonie Ki Man-fung, vice-chairman of the public relations committee of Unicef, said the idea of "playing" should include interaction with others, and children should have a say on how they want to have fun. "Of course, that doesn't mean children should skip meals and classes so they can play," she said.
Ki said Unicef had always had close ties with the Hong Kong Cycling Team, and that Lee was chosen because of her positive image.