The Legacy Awards have been created to recognise those who show particular goodwill, passion and kindness in their acts - which is something Princess Diana was known especially for.
To mark the occasion Prince William took to the podium to reflect on his mother's own legacy, remarking that this year will be the 20th since her death.
He said, 'This summer marks 20 years since our mother died. She was taken at only 36, just slightly older than I am today.'
The father-of-two continued to reflect on some of the great work his mother achieved, mentioning in particular her services to the homeless and AIDS victims.
'She achieved so much in her life. From helping to shatter the stigma around AIDS, to fighting to ban landmines and supporting the homeless - she touched the lives of millions.'
Princess Diana pictured in 1985 with her two sons, Harry and William.
Prince William appeared to get emotional as he explained that though his mother is gone, her positive influences live on.
'Of course, we can never know what our mother would have gone on to do, but in one sense Harry and I feel that our mother lives on in the countless acts of compassion and bravery that she inspires in others.'
William's younger brother, Prince Harry, also took to the stage, revealing some of Princess Diana's private efforts.
'One of the things our mother taught William and I was the value of doing good when no one is watching.
'She visited hospitals late at night to comfort patients; she spent hours writing letters to privately support the work of others; she achieved a lot by shining a spotlight, but she worked just as hard when the cameras were gone.'
Addressing the 20 Legacy Award winners who are all aged between 11 and 18, Prince Harry said, 'We are so pleased that her name is being put to good use by the Diana Award to recognise young people who are making a mark in the world around them.'
Prince William and Prince Harry standing with the 20 Legacy Award winners.
'You should be absolutely proud of what you've started and what you've achieved, you're still in your teenage years - don't stop now guys,' he added.
The winners included youth from all over the world, with some hailing from countries such as Canada and India and were chosen for their 'monumental impact on society'.