That didn't take long! Less than three weeks after giving birth to daughter Rainbow Aurora, Holly Madison is back in red-carpet-ready shape. The new mom and former Playboy model, 33, showed off her sexy post-baby body at Cirque Du Soleil's World Water Day celebration on Friday, March 22.

PHOTOS: Holly's maternity style

Arriving at the Hyde Bellagio in Las Vegas, the Girls Next Door alum was radiant in a blue fit-and-flare frock, belted to show off her narrow waist. She paired the sweet dress with black heels and her usual super glam blonde curls.

PHOTOS: Holly's Girls Next Door days

Madison and boyfriend Pasquale Rotella welcomed their first child on Tuesday, March 5. "I couldn’t be more blessed to have such a perfect daughter and have never been happier than I am now!" she wrote on her blog shortly after Rainbow's birth. 

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Defending her little girl's colorful moniker, she added: "There are a lot of smug haters out there who bag on my choice of a name, but I don't care about what they think. I want my daughter to be proud of who she is and learn to speak up and stand up for herself at a young age."

"I spent most of my life being a people-pleaser who worried about what other people thought or thought was cool," she continued. " And I don’t want that for her."

This article originally appeared on Holly Madison Shows Off Slim Post-Baby Body Three Weeks After Giving Birth to Daughter Rainbow: Picture