Youth workers, businesses leaders and celebrities joined supporters of the charity last week at the anniversary event hosted by the charity's patron, Princess Anne.
The Positive about Youth message launched at the event has been backed by a number of politicians, sports personalities and celebrities including film director Guy Ritchie, MP Natascha Engel, chair of the All Party Parliamentary Group for Youth Affairs, and champion Olympic rower Katherine Grainger.
Nigel Mansell, the charity's president and former Formula One world champion, said: "I support Positive about Youth because if we celebrate youth, their achievements and their contribution to our communities we will all be the richer. Please join us and let's make a real difference to the way we value young people."
During its centenary year UK Youth will be taking the Positive About Youth message to major arts and sports events around the UK including the Hay Festival, the London Marathon and Wimbledon.
In addition, Mansell will be cycling around the UK on a 1,200 mile journey to draw attention to the campaign and raise money for the charity.
John Bateman, UK Youth chief executive, said: "We will use our centenary to change the country's perceptions of young people. More than 70 per cent of media coverage about young people is negative yet the vast majority of young people are achieving great things and playing an increased role in communities all over the country.
"We want to highlight these activities, raise the aspirations, realise the potential and recognise the achievements of all young people thereby improving their life chances."
