Is Princess Leia a Disney Princess?
To answer your question, yes she is.
On the day that George Lucas signed the contract, that handed all rights of Star Wars over to Disney, that afternoon, Princess Leia was moved from her cell in the Death Star Detention Centre to a finer establishment, fit to suit a princess; the Disney castle. There she was welcomed by every Disney princess from Aura to Cinderella and not to mention Alice (who came out of the rabbit hole for this event).
At first Leia felt out of place among the ladies for whom interest rest in: fashion, Princes, books and flowers. Much unlike Leia's interests of: blasters, star ships, lightsabers and the Death Star.
Leia became acquainted with a few of her fellow princesses, over a light afternoon tea of scones, jam and cream and tea served in elegant china cups and saucers. Rapunzel asked why Leia wore her hair in two buns, on the sides of her head; Leia replied that she liked it that way and it resembles the style that was traditionally worn, by high society women of Alderaan. When Leia told the ladies that she had fallen in love with a smuggler and made out with her twin brother, the princesses were all disgusted. Leia finished it off nicely, when Ariel and Belle asked her what her interests were.
"Um…," Leia replied. "Shooting storm troopers, flying shotgun in the Millennium Falcon, destroying the Death Star and wearing a metal bikini."
It turned out that to the princesses, that Leia wasn't just a stranger from a galaxy far far away; she was a fellow princess a fellow sister.