WATCH: This 'All I Want for Christmas' star-studded Carpool Karaoke will give you all the festive feels
This one was a year in the making.
Mariah Carey joined The Late Late Show host on Thursday night in belting out her festive classic All I Want for Christmas.
But the segment soon turned into a star-studded sing-a-long as it cut to clips of famous faces from previous episodes also singing the same track.
Adele, Lady Gaga, Chris Martin, Justin Bieber, Red Hot Chilli Peppers, Jennifer Lopez, Gwen Stefani, Selena Gomez and a host of other celebrities joined in the feel-good celebration.
Apparently, Corden had the idea for this Christmas mashup since the start of 2016 and managed to get each celebrity to film their All I Want for Christmas segment throughout the year.
"Very few things that you can say you have worked on for a whole year. This one we can," producer Ben Winston wrote on Twitter.