The bash took place Sunday, weeks ahead of the teen sensation's Nov. 23 birthday.
Disneyland said about 5,000 party guests sang "Happy Birthday" to Cyrus, the star of the Disney Channel series "Hannah Montana."
Among those invited were special guests from Youth Service America, an organization that Disneyland says "shares her passion for promoting youth volunteerism."
Disney Chief Executive Officer Bob Iger presented a gift of $1 million to the group Sunday on behalf of Walt Disney Parks and Resorts.
"I always love coming to Disneyland but celebrating my birthday here with my family, friends and the kids from YSA is really awesome!" Cyrus said. "This is a night I'll never forget."
Cyrus treated the crowd to a performance of four of her songs, as well as a duet with her country music star dad Billy Ray Cyrus.
The night ended with a birthday cake and fireworks display at Sleeping Beauty Castle.