Christmas would be a lot less merry without Mariah Carey's "All I Want for Christmas Is You," which is why the diva will be taking over NBC this holiday season to spread the Yuletide Cheer.

Mariah kicked off her "12 Days of Christmas" blitz Wednesday morning with an appearance on the Todayshow.  In the coming weeks, she'll make appearances on all three hours of the show, and will also appear on Access Hollywood, Extra, Bravo's Watch What Happens Live, MSNBC's PoliticsNation and more.  She's also a guest star on Michael Buble's upcoming holiday special, airing on NBC December 18.

Topping it all off will be Mariah's headlining appearance on NBC's New Year's Eve telecast.  More details about that will be announced later.