Pixie is among the first few celebrities to arrive at the event, which will include a main ceremony presented by Ant and Dec.
The 2013 'X Factor' winner hasn’t appeared in public since announcing that she’s expecting her third child with husband Craig.
Prince Charles, the charity's President, is also attending to show his support for award winners and nominees.
The awards celebrate the achievements of young people who have triumphed in the face of extremely tough conditions, including homelessness and drug addiction.
The Celebrate Success Awards are in their 10th year and the Prince’s Trust have been busy reminding everyone of previous winners’ success in the run-up to the 2014 ceremony.
The Mappin & Webb Young Ambassador of the Year Award in association with the Huffington Post recognises young people who volunteer their time, share their personal experiences and inspire others.