Offscreen, though, this 15-year-old phenom is starting to learn how hard it really is to have the best of both worlds: as a G-rated Disney superstar AND a real-life, growing teenager with an eye on a long career.
Cyrus, whose fresh, easy charm and down-home southern appeal have catapulted her to an astonishing level of celebrity, especially in the past year, found herself having to apologize Sunday for some entirely un-Miley photos in Vanity Fair magazine.
But Cyrus IS 15, with a fan base that begins in preschool. And it's what the photo suggests rather than shows - the idea that she might be nude, perhaps even in bed - that bothered some parents who poured their feelings onto blogs over the weekend. She wan't nude during the shoot, nor in bed, but she does have a subtle come-hither expression.
Leibovitz said Monday that she and Cyrus had discussed the photos beforehand, and Vanity Fair said "Miley's parents and/or minders were on the set all day ... everyone thought it was a beautiful and natural portrait." As for Disney, it accused editors of creating a situation "to deliberately manipulate a 15-year-old." Disney declined to make anyone connected with "Hannah Montana" available to speak for this article.
Unfortunately for Cyrus, the photos, taken in February, might not have made nearly such a splash but for a bit of awkward timing: They emerged just days after some attention-getting amateur shots of Cyrus hit the Web. In one, she tugs down a tank top to reveal a bright green bra. In another, she lies languidly on her back across a male friend, shirt raised to bare her midriff.
So the timing was terrible. But some celebrity watchers saw the developments as an attempt by Cyrus and her handlers - while not necessarily calculated - to look ahead a few years, beyond the tween audience.
"She has to find a way to gain a new following," said Peter Castro, deputy managing editor of People magazine. He likened her situation to that of a butterfly still trapped in the cocoon. "She began as a caterpillar, and made a lot of money that way, but now she doesn't know which way to go. She's thinking, soon I've got to be a butterfly."
Biological analogies aside, Cyrus' predicament evoked plenty of references to the cautionary tale of Britney Spears, who started on the Disney Channel about the same age as Cyrus and had her first huge hit, "Baby One More Time," at age 17.
"Britney was in a Miley place," said Castro. Then she decided to break out, making her persona in "Baby One More Time" a sexy schoolgirl, and doing a provocative photo shoot for Rolling Stone. "She alienated parents, but gained a whole following of older kids," says Castro.
But, he added, "I don't know that Miley could get away with that. I think her dad and management team are closely following Britney's career, saying, 'Don't let this ever happen to you."'
Unlike the 26-year-old Britney of today, for whom the phrase "train wreck" has become an unwelcome cliche, the self-possessed and upbeat Cyrus has worn the title of "role model" easily. She has been utterly scandal-free until now, unless you count her failure to wear a seat belt during a car ride in her concert movie (her dad apologized for that, too).
"Miley's at the very top of our celebrity list," said Joanna Saltz, executive editor of Seventeen magazine, whose average reader is between 16 and 17. While Spears never appears in Seventeen, readers love Cyrus, Saltz said, because she seems genuine, unproduced, comfortable in her own skin.
"And she's just exploded," said Saltz. "A year ago she was the queen of tweens, and now she's a favorite of our readers. She's crossed all age groups."