All of our favorite E! celebrities including Kim & Kourtney, Chelsea Handler, and newcomer Ryan Lochte arrived at the 2013 E! Upfront last night for a serious party!

E! News commentator Guiliana Rancic looked super thin wearing a black sheath dress with a floral necklace, while her partner in crime, Kelly Osbourne was showing off her new toned body in an adorable baby doll dress.

When Kim Kardashian arrived to the party, she surprised no one in a black satin dress with long sleeves. The mom to be has been keeping covered lately in all black ensembles. It may be due to the widespread criticism she's received for her outfit choices during her pregnancy, but we think she looks fabulous.

Some other notable guests were Ryan Lochte in a sharp 3-piece suit, Kim's mother Kris Kardashian in a fiery red dress and fashion police host George Kotsiopoulos wore a bright yellow blazer similar to Brad Goreski's the night before.

Click through the gallery to see all the biggest names on E! celebrating the 2013 E! Upfront.