The Take Me Out host will be joined by Ant & Dec, Phillip Schofield, Holly Willoughby and Christine Bleakley for the live show on Friday, December 21 on ITV.
Text Santa, which launched last year, raises money for specially chosen charities, which this year include Age UK, Anthony Nolan, Carers UK, Marie Curie Cancer Care, Together for Short Lives and Whizz-Kidz.
The evening's entertainment will include mini-episodes of ITV's leading shows, including a festive Coronation Street with special guest cameos.
Ant & Dec said: "We're delighted to be returning to host Text Santa again, last year we raised an amazing amount of money and awareness for six truly worthy causes. This year we want to make it even bigger and better and you can get involved too by simply ordering a fundraising pack and putting the fun into fundraising."
McGuinness commented: "I'm rocking around the Christmas tree at joining the Text Santa team. What a great bunch of people to be working with to host this year's appeal. Santa has been very kind to me this year and paired me up with Christine Bleakley! What a fantastic way to start the Christmas countdown!"
Viewers will once again be able to donate via text using JustTextGiving by Vodafone, free on any network, allowing 100% of the donation to go to the charities.
ITV director Peter Fincham said: "We're so thrilled to be working with such fantastic names again and that so many of ITV's most loved shows are also doing something special for Text Santa. We want to give viewers a real treat in return for their incredible generosity and support of these inspirational charities."