Hi Chekena!
Thanks for your question.
Mickey's Very Merry Christmas Party is probably our family's favorite holiday event that
Disney World annually hosts. From the Once Upon a Christmastime Parade, to the performances, and of course
Minnie's Wonderful Christmastime Fireworks, it is a night of holiday wonder at
Disney's Magic Kingdom!
Disney guests who purchased
Mickey's Very Merry Christmas Party tickets are issued special wristbands acknowledging they've paid for the event. Sometime a little before 7PM (the time the party actually begins), guests without tickets are escorted outside of the theme park. So although you may have a ticket for that day at Magic Kingdom, if you don't have a party ticket or wristband, you will be asked to leave before the party begins (the fireworks show happens a little later in the evening of the party).
If you don't want to miss this special event, consider purchasing a ticket to Mickey's Very Merry Christmas Party, and perhaps saving your Magic Kingdom ticket for another day if you can.
Have a Mickey Magical Day!
Terry