Kelly Osbourne certainly knows how to make an entrance! The Osbournes star celebrated her 40th birthday in high style, stepping out in a chic and classic little black dress that showed off her stunning transformation.

Kelly wore a black off-the-shoulder dress from Vivienne Westwood for the occasion, accessorizing with a sparkly black hair bow and a strand of pearls, which was the perfect attire for blowing out the candles on a three-tiered "Kelly No. 40" cake.

Kelly Osbourne looked sensational as she showed off her six-stone weight loss at her 40th birthday party in Los Angeles, after shedding an impressive 85 pounds

Kelly Osbourne showed off her eight-stone weight loss as she celebrated her 40th birthday in Los Angeles, wearing a black corset to accentuate her tiny waist.