Rebecca's entry, a video slideshow with a poem, beat the 24 other shortlisted entries.
Some of the other nominated towns were Blackpool, Aberdeen, Chester, Milton Keynes and Wigan.
Rebecca plans to take her niece and nephew to the naming ceremony
Rebecca will now fly to Florida with her nephew Aaron and niece Amy, to unveil the 'Walt Disney World Twinned with Swindon' sign.
"My wish was always to be Cinderella with a beautiful ball gown, so I'm really looking forward to dressing the part for the twinning ceremony in January," she said.
"It will be so exciting to see Swindon's name alongside Walt Disney World on the sign in Florida."
She'll then bring home a sign to be put up in Swindon.
"Rebecca's video entry was selected for its creativity, sense of fun and the way in which it showcases the elements of Swindon that reflect key aspects of the Walt Disney World Resort in Florida," a Walt Disney World spokesperson said.
Hugh Wood of Disney Destinations International said: "Rebecca's video really stood out.
"Her local pride and creative approach, coupled with her obvious knowledge of Walt Disney World just made the difference.
"We're looking forward to building a friendly and magical relationship with our new twin, Swindon," Mr Wood said.
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