Welcome to planDisney, La’ Asia! It looks like you’ll be visiting Mickey and Minnie’s Florida home during the most wonderful time of the year!
Magic Kingdom Park is always perfect, but it’s got just a little extra magic at Christmastime! You’ll love the decoration along Main Street, U.S.A. during the holiday season!
I’m glad you asked your question! The Christmas season tends to be busy at the Walt Disney World Resort. Magic Kingdom Park is particularly busy because of how festive it is. In short, yes, it is possible to be denied park access or re-entry, even with a dining reservation, if the park reaches capacity. The dates during Christmas week that I’ve seen Magic Kingdom Park reach capacity are usually Christmas Day through New Year's Day with those two days, and New Year’s Eve, being the most popular.
The best strategy I can recommend for being able to stay in Magic Kingdom Park during a potential “high capacity” day is to plan on making a day (and night) of being in the park. Arrive at park opening time and enter the park. Once you’re in the park, you’re in! However, if you leave the park, and it reaches capacity, you might be denied re-entry. Plan on making it a fun day! Book a table service dining reservation (or two)! And, plan on staying hydrated and getting off your feet. I recommend attractions that allow you to sit for a few minutes –
Mickey’s PhilharMagic (my favorite),
Monster’s Inc. Laugh Floor, and the
Tomorrowland Transit Authority PeopleMover are great attractions for taking a rest (while still having fun!)
Have a magical visit, La’ Asia! Be sure to check out Mickey's Once Upon a Christmas Parade at Magic Kingdom Park during Christmas week! I hope all your Christmas wishes come true at the Most Magical Place on Earth!
Dreams do come true!
Jonathan