Credit: Denise Truscello/WireImage

Major curves ahead!

It's not every day Kim Kardashian's little bro celebrates his quarter-century birthday, so for the special festivities, she made sure to get decked up in a head-turning outfit.

At Rob Kardashian's 25th birthday bash at 1 Oak in Las Vegas Friday, Kim slipped into a sexy, asset-hugging white mini dress decorated with patches of silver sequins and cut outs on the shoulders.

Kim and Rob's mom, Kris Jenner, was also at the fete and donned a chic red dress.

"Happy Birthday Robbie!!!!" Kim, 31, tweeted along with a photo of the three of them via Instagram.

Although Rob's other older sisters weren't in attendance, they still gave shootouts with family pics on their respective personal blogs Saturday.

"Happy Birthday to the best brother in the world! I CANNOT believe you are 25!!! Truly I can't!," Khloe, 27, wrote. "God blessed me with an amazing brother. Our bond is unbreakable, even though I want to strangle you sometimes, I still adore you!"

"Sending lots of love to my baby brother Rob today on his 25th birthday!!" Kourtney, 32, posted. "Rob, I am so proud of the man you have become. Here's to an amazing 25th birthday… I love you so much!"

Prior to hitting Rob's luxe bash, the family (sans Khloe and Kourtney) stopped by the Kardashian Khaos store in the Mirage Hotel -- with Rob's leggy half-sisters, Kendall, 16, and Kylie, 14, in tow.