Kevin Mazur, WireImage
Demi, 19, is co-hosting the party, which airs Dec. 31 at 11PM EST on MTV. Meanwhile Selena, 19, will be joining fellow performers Jason Derulo, Mac Miller and J.Cole on the live stage for the event.
The Disney darlings-turned-solo-pop-stars first forged their friendship as co-stars on the children's TV show 'Barney' when they were both just 8-years-old.
The Disney Channel duo found their friendship put to the test as Demi's emotional and mental health problems landed her in treatment at the end of 2010. Happily, Demi has since credited Selena for helping her get through the tough time in rehab, and since her release in January 2011, the buds have rekindled their friendship.
While Selena's boyfriend Justin Bieber is busy performing at Dick Clark's New Year's Eve special, she'll get to spend some quality time with Demi. Girls' night out!