katy perry white dress high slit met costume institute gala

Katy Perry showing some serious leg at the Met Costume Institute Gala. Photo: Kevin Mazur, WireImage.com

Looks like all that Proactiv has really paid off for Katy Perry!

The "One of the Boys" singer and acne-treatment pitchwoman has landed the top spot on Maxim's Hot 100 List of beautiful women.

The lad mag says the 25-year-old brunette bombshell earned the honor because she is both sexy and talented; "the best friend you suddenly realize you've loved your whole life. The rad chick who taught you how to skateboard and whistle and also looks unbelievable in a bikini."

That description isn't so far off. Perry -- who is engaged to British comic Russell Brand -- grew up a squeaky-clean pastor's daughter before transforming her look and persona.

"I've gone from Betty Boop to more Bettie Page," she tells June's Lucky magazine of her recent style evolution.

Though natural blonde Perry -- who told UK Glamour she counts Dita Von Teese, Agyness Deyn, Bjork, and Lolita among her beauty icons -- has altered her appearance over the years, she insists those changes have never included plastic surgery.

"How could people think these are fake? Look at them. Ask them," Perry has reportedly said of her breasts.

"They are as real as real can be. One hundred per cent genuine and untouched ... well sort of."

Joining Perry in the top 10 on Maxim's Hot 100 list: Sports Illustrated Swimsuit Edition cover girl Brooklyn Decker; actresses Zoe Saldana, Blake Lively, and Megan Fox; singer Rihanna; George Clooney flame Elisabetta Canalis; "Iron Man 2" star Olivia Munn; reality star Kim Kardashian; and Victoria's Secret supermodel Marisa Miller.

Meanwhile, check out who was recently named World's Most Glamorous Woman.