Jingle Ball 2011: Stars Attend KIIS FM's Annual Concert (PHOTOS)

12/05/2011 08:56 am ET | Updated Feb 04, 2012

Ignore the weather and the calendar, it's officially the holiday season. How can we be so sure? Because December 3 was Jingle Ball!

From the outrageous Lady Gaga to the hair-whipping Willow Smith to Jennifer Love Hewitt, who donned a Christmas-red (and very low-cut) dress, Hollywood's biggest came out to celebrate KIIS FM's annual concert.

Take a look at the stars who were there to share in all that good cheer!

PHOTOS: