The 'Wrecking Ball' singer is said to be hosting a S&M-themed bash to celebrate the milestone later this month and even invited ex-fiance Liam Hemsworth, reported Femalefirst.
"Miley wants the party to be off the hook, she's hiring all sorts," a source said.
Although Cyrus will be performing at the American Music Awards on her birthday on November 23, she will be hosting the event afterwards with big showbiz names on the guest list.
The 20-year-old singer is said to be in contact with Hemsworth, who she split from in September after a three-year relationship.