Radar Online reports that Chenoweth (Wicked, "Pushing Daisies") and Applegate (Sweet Charity, "Samantha Who?") taped a 1960s medley with Underwood for the upcoming special at CBS studios in late October.
Previous announcements also reveal that 9 to 5 composer Dolly Parton, "American Idol" winner David Cook and Brad Paisley will also guest star on "Carrie Underwood: An All-Star Holiday Special."