Christmas 'Carpool Karaoke' is here and it's better than we ever could have hoped. It seems James Corden has been planning this all year, secretly getting all his previous guests to sing along to Mariah Carey's 'All I Want For Christmas Is You' for a mega karaoke montage.

Mariah CareyMariah Carey appears on Carpool Karaoke

An uber glamorous Mariah Carey joined a Christmas jumper wearing James Corden for 'The Late Late Show''s best segment 'Carpool Karaoke' last night (December 15th 2016), helping the latter out with a spot of Christmas shopping. As they drove along in a car full of wrapped Christmas presents and a tree strapped to the roof, the singer revealed her holiday wishes.

'I don't know, I don't want to ask for something too expensive', she began, as James pressed her. 'I want you to sing my song 'All I Want For Christmas Is You'.' Needless to say, he did, with the help of several former 'Karaoke' passengers. As they kick into the song, it cuts into a never before seen clip of Adele singing along to the song from her London edition of 'Carpool Karaoke' back in January. More guests include Demi Lovato and Nick Jonas, Elton John, Selena Gomez, Lady Gaga, Chris Martin, Red Hot Chili Peppers and Gwen Stefani.

'All I Want For Christmas Is You' is among the greatest Christmas classics ever written. Released by Mariah Carey in 1994, it was the lead single from her fourth studio album 'Merry Christmas', which also happened to be the first of two holiday albums - the second of which was 'Merry Christmas II You' released in 2010. The song itself was a number one smash hit and remains to this day as the eleventh best-selling single in history with more than 14 million sales.

More: Madonna appears on 'Carpool Karaoke'

We wonder what song he'll pick next Christmas.