He has been joined by Britain's Got Talent stars Ashleigh and Pudsey, girlband Stooshe and others as part of the campaign.
"I've been so blessed with all the support I've had from everyone during the X Factor competition and I really wanted to give something back this Christmas," Douglas said.
"Text Santa is raising awareness and funds for great causes, and to support, all you need to do is head to Asda and buy a Text Santa hat to donate to the amazing charities that will benefit."
Douglas and the other stars have joined forces for a Christmas fundraising video to raise money for charities that offer life-changing services to vulnerable people throughout the UK.
Asda will donate £10,000 to Text Santa for every 100,000 views of the video on its YouTube channel.
The Text Santa appeal culminates in an ITV1 show hosted by Christine Bleakley, Paddy McGuinness, Ant & Dec, Holly Willoughby and Phillip Schofield on December 21.
Asda is selling official Text Santa hats and Sketch Santa celebrity cards across the country.
Hats are priced at £1 (with a 15-33p donation made to Text Santa) and £2 for the flashing design (72p donation made to Text Santa). Packs of Text Santa charity cards are priced at £2.