Lively, 22, donned a low-cut ruby red Versace gown, Christian Louboutin shoes and Lorraine Schwartz jewels.
"You can do no wrong tonight," said E! personality (and America's Next Top Model star) Jay Manuel.
Added Real Housewives of Atlanta's NeNe Leakes: "It's a little sexy!"
Leighton Meester, 23, paired her floor-length Bottega Veneta chiffon gown with bright red lips.
"I think the shoulder pads are cute!" Leakes observed.
Snapped back Manuel: "Those are not shoulder pads! Those are stylish knots!"
Tell Us: Which Gossip Girl star looks hotter at the Emmys?