Jack Osbourne and Kelly Osbourne arrive at the screening of "God Bless Ozzy Osbourne" to benefit the Musicares Map Fund held at ArcLight Cinerama Dome in Hollywood, California. Credit: Jeff Kravitz/FilmMagic

Her niece Pearl isn't even two weeks old, and already Kelly Osbourne can't stop gushing about the benefits of being an aunt.

"[Pearl's birth] is the most amazing thing that has ever happened to our family," she told Us Weekly at Friday's BritWeek: An Evening With Piers Morgan event in Los Angeles. "I could not be happier."

Once she met her brother Jack and his fiancee Lisa Stelly's little girl, it was "love at first sight" for the E! Fashion Police cohost.

In fact, being around the newborn -- whom Stelly welcomed April 24 -- has even made her think about having her own family some day.

"[Pearl's birth] made me realize how badly eventually I want to have children, but it also made me realize I'm not ready yet," Kelly, 25, explained.

Jack, on the other hand, is already a natural father, his sister says. "He's just so happy and he's so good with the baby," Kelly confirms. "It's unbelievable."